In the current domestic engineering general contracting projects, the design and construction are conducted independently without deep integration and collaboration, which often fails to maximize the limited project investment value, and goes against the original intention of the country to vigorously promote the engineering general contracting model. How to truly integrate design and construction is to achieve the original intention of EPC engineering general contracting. Based on the practice in the Taihe Road Viaduct Restoration and Maintenance Project, the integration path of design and construction in general contracting projects are explored and analyzed, and the mechanism for the design to play a leading role is expounded. In terms of overall project control and the integration of design and construction, the detailed introductions are made in combination to the application scenarios and specific cases, which has the effective guidance and reference for construction units or design enterprises to carry out the engineering general contracting business.