【正文】 actor or organization in the past has been pleted similar projects, and to maintain the various records of the actual cost of the project, these historical data to estimate the current cost of the project, play a guiding role in the process. Cost estimates should be a powerful but also rational. So they should not be too heavily for possible errors or fill them for everything including contingencies funds. If the cost estimates are too conservative, and the estimated total cost of the project may exceed the customer willingness to pay the contractor or higher than that of other petitors estimate. On the other hand, if the cost estimates are too optimistic and overlooked some unexpected expenses, the contractor or may be losing money (in the pricing contract) or have to face to the customer to obtain additional funding to the embarrassing cost overruns.Effective cost control is the key to the law in a timely manner on the basis of cost performance. Early identification of cost difference is crucial and cost ineffective, and this may worsen the situation prior to take timely and effective measures. Once the project costs out of control, it is necessary to plete the project within budget plan is very difficult. Cost control include the following: 1, the analysis of cost performance, determine which packages need to work to take effective action. 2, decided to take any special effective action. 3, edited projects including the time and cost projections, which include the effective action. Cost analysis should include recognition of achievement who have a negative difference between the cost of performance or cost index less than 39。s work packet. At the same time, it should be in the previous reporting period to identify the differences in cost or cost performance index has been deteriorating work packet. In order to reduce costs or improve work efficiency, we must have the negative difference between the work of the package to focus its efforts on improving measures. By these measures focus its efforts on the priority should be modified by the difference between the total cost to decide, that is, have the greatest negative cost difference should work with the highest priority packets. When a negative assessment of the difference between the cost of the packet, you should focus on measures to take effective action to reduce the activities of the following two types of costs:1, will be held in the near future activities. Not a longterm plan to reduce the scheduled activities at the cost, if these implementation of effective action in the near future, you will receive immediate response to the results. If you take effective action to postpone implementation until the longterm future implementation of a moment, then before this, the cost difference will be negative and further deterioration. As the project forward, can take effective action to the remaining time will be less and less. 2, the estimated cost of the activities An effective measure taken, the cost is only cost $ 20,000 activities 10%, with the total estimated $ 300 activities, can have significant results. Usually, the greater the estimated cost of an activity, the greatest extent greater opportunities to reduce costs. To reduce the cost of the activities of a variety of different methods. One method is to use the relatively low price and meet the functional use of the material. Also that they can go to another supplier, but he can supply the same lower cost materials. Another approach is to arrange a wealth of expertise or experience to plete the people supporting this activity or to obtain better results.In addition, one way to reduce costs is to narrow the scope of the work packages to reduce some of the specialized equipment or activities. For example, started as a program, a contractor can only decided to reairs with a paint brush rather than a room. Through an improved method or technology to gradually increase output to lower the cost of another method, for example, by hiring an automatic sprinkler paint equipment, operators can be substantially reduced through the use of rollers and brushes to paint brush in a room the cost and time. In many cases, the difference reduce future costs will include reducing the scope of the project or delay the project schedule. If the cost of a very large negative, or to reduce the scope of work to lower the quality control investment in the project budget is very necessary. All of the project scope of work, budget, work plans, quality in the reduction of depression may face of a crisis, in certain circumstances, customers and contractors or project team may need to know which one or more of these elements hardly pleted, which may cause customers to spend additional funds to make up for expected cost overrun, or on who caused the cost overruns, customers or contractors in the two who should pay these additional costs arising from the contract dispute.Effective cost control is the key difference once found negative cost, the cost immediately targeted invalid. To take effective control measures, rather than fatalistic hope that things will change as the project move forward and good. Have control early in the morning on the cost of the scope of work and time will affect relatively few. Once the costs out of control, the project budget to plete all work, may need to extend or reduce the scope of the project construction period, even if the only good when the project cost difference of cost control differences in the direction of change or deteriorate very important. If the cost performance is good, it should make the greatest efforts to maintain such a situation. Once a project has a cost of the plight of poor performance, then let it return to the normal track of the original is a difficult task.