In this paper, a time-cost-quality trade-off optimization model is set up by using multi-objective optimization theory and multi-attribute utility function theory. By applying network planning techniques and genetic algorithms to the model, the most satisfied decision result as well as several near satisfied alternative results can be obtained, which can be used to control the project investment. In the paper, a case study is given to verify the feasibility and practicability of the model. The application analysis and the results show that the model has practical value to some extent.