The market competition under globalization promotes enterprises to integrate resources all over the world, and the decision-making of outsourcing is becoming an important influencing factor of project scheduling. Taking subproject TCP/C1-3-1A-1 of Three Gorges Project for example, this paper constructs module network by design structure matrix, and chooses outsourcing module primarily by two levels, then formulates optimization model of project scheduling based on modular outsourcing. The results show that the income of the project is enhanced and the duration of the project is greatly shortened because of synergy effects with modular outsourcing.