Abstract: Time and costs are considered as the major criteria in a project and project managers always seek to finish projects in the shortest possible time spending the lowest costs to obtain success in projects. One of the major challenges in this regard is to select a proper approach in order to achieve the above goals. Since, costs and time are regarded as two major aspects in doing construction projects, the purpose of this research is to optimize these two factors. In the process of optimizing the period of doing the project, a tolerance is considered for the project costs, so that the optimal conditions in the acceptable range for the costs and time of doing the project are specified. The genetic algorithm has been utilized in this research for optimization of the project time and costs. The critical chain method has also been used for project scheduling.