Tri-objective optimization of time, cost and quality is complex and valuable research hotspot which is of expansive practice application foreground. Exact method can only solve some small scale optimization problem, but the practice problem is usually large scale. In order to analyze and research the complex large scale optimization problem, the integrative optimization model of time-cost-quality is set up according to the action rules and relations of three objectives. Tri-population genetic algorithm is put forward for the optimization model based on the idea of intellective stochastic search. The algorithm adopts different populations to carry out the parallel search to realize rapid optimization. Finally the methods put forward are applied to manufacturing case of airplane part, and a series of optimization result is achieved. The case application validates the correctness of the model and the availability of the algorithm.