Determining the total price of construction projects and effective control of investment are not only important components of construction project management, but also directly related to the economic benefits of investment institutions. Taking 4 different construction schemes of an oil depot as examples, the project cost evaluation index system is constructed. On this basis, technical and economic analysis was introduced through cloud model, classification standard was established, and entropy weight method was used to determine the weight of all grass⁃roots indicators. Finally, four construction schemes were evaluated based on cloud model generator. The results show that the order of membership of the schemes is M1＞M3＞M2≈M4. The peak point of M1 appears earliest, between 2.0 and 2.5, and the peak point of M4 appears later. The influential basic indexes are fire protection engineering, foundation engineering, heat insulation engineering and project measure cost, of which the measure cost accounts for more than 1/10 of the total project cost. Therefore, on the premise of ensuring the construction requirements, we should strengthen the control of the project cost in such aspects as fire engineering, foundation engineering, thermal insulation engineering and project measure cost, so as to achieve the purpose of the optimal design and the most economical investment in the construction of the best project.