Abstract: Abstract: To change the present situation that the project cost management is only limited to the construction stage or even the project budget and settlement work, the project cost management should be carried out throughout the whole project management process, such as project decision-making, project design, construction supervision, completion settlement, project audit, etc., and the whole process of control and management should be fully developed. It is a necessary measure to control project cost effectively and an effective way to improve project management level to exert its management functions such as evaluation and control. In the whole control process, project decision-making and design is the decisive stage. It has become a common consensus of construction units to move the project cost management to the project decision-making and design stage. This paper focuses on how to strengthen the cost management of project decision and engineering design stage.