The PERT network diagram optimization and the node layout optimization were studied in order to solve the difficulty of using manual methods to generate the PERT network chart in large-scale software project management. The new methods of optimization the node of PERT was proposed based on ant colony optimization algorithm (ACO) and genetic algorithms (GAs). The high adaptability and population optimization technology of GAs are discussed and also the ACO is introduced to realize the nodes layout global adjustment. In the end, calculation and simulation results show that the methods proposed can make the number of nodes of PERT network diagram generated automatically minimum. Meanwhile, it can make the layout of nodes of PERT network diagram more efficient and effective, so as to effectively solve the large-scale software project assessment problem.