Job shop scheduling in the production management module is one of the core of ERP system. To solve the problem, that is, to discretely manufacture the multi-process routes and the multi-objective job shop scheduling, this paper propose an optimized algorithm of the improved particle swarm that is used to establish the mathematical model which turns in the direction of the production scheduling system of ERP-based. And with the example of an engineering machinery manufacturing enterprise, it deduces a model’s realization process in the multi-objective shop scheduling in the discrete manufacturing of more complex product structures. It finally gives integration framework of production scheduling system based on the real-time capacity balance, which are based on the particle swarm optimization (PSO) algorithm, and together with the other modules of ERP system. It provides an important practical value for discrete manufacturing enterprises using ERP system to realize scientific and effective production operation management.