Abstract: A multi-objective optimization method for tasks scheduling of large-scale engineering project is proposed.In the method，a multi-objective programming model is established with the objective to minimize the completion time and total expenses and to maximize the total quality of the project.Considering the model’s characteristic of multi-vary，multi-restriction and large solution space，a hybrid algorithm named improved ant colony algorithm based on adaptive mutation probability and simulated annealing thought is proposed.The application in a large-scale engineering project tasks assignment example validates the correctness and effectiveness of the method.