In order to solve the problem of project schedule delays caused by resource conflicts and uncertainty of the environment, work duration, and logical relationship, this paper proposed CCPSP (critical chain project scheduling problem) optimal scheduling model which integrates CCM (critical chain method) and multi-level GERT (graphical evaluation and review technique) network. DEACA (differential evolution ant colony algorithm) is designed to solve the problem, in which DE (differential evolution algorithm) is used to deal with the cross problem and mutation problem, and ACA (ant colony algorithm) is used to deal with each stage of the optimization process. The activity resource list is used as the coding rule of each feasible scheduling solution. The activity resource list is used as the coding rule of every feasible scheduling solution, and the activity list is generated by roulette using pheromone and heuristics. Insert and swap neighborhood search structures are introduced to optimize the solution iteratively, and the Pareto file is used to save the non-dominated solution, which is updated in each generation of ant colony search. This paper makes full use of the advantages of the two algorithms to achieve fast convergence and a global search for optimal solutions. At the same time of seeking the optimization algorithm, considering the multiresource constraints, environmental uncertainties and other factors of the project, a buffer is set up, and a "minimum duration-maximum robustness" project schedule is formulated. Finally, through the analysis and verification of the project example, it shows that the project schedule made by this method is feasible. INDEX TERMS GERTs (graphic evaluation and review technique simulation), CCM (critical chain method), CCPSP (critical chain project scheduling problem), Schedule plan, DEACA (Differential Evolution Ant Colony Algorithm), schedule buffer