Production scheduling is an important function that determines the efficiency and productivity of a production system. Many optimization methods, techniques, tools, and heuristics have been used to solve production scheduling problems, accordingly priority rules are implemented for customers' orders in real-world applications. Simulations and heuristic methods are quite useful for making decisions, and they are used mostly to design and improve production systems by reducing their complexity. In this study, a Priority Rule-Based Genetic Algorithm Scheduling (PRGA-Sched) module was developed to provide shorter total completion time in production scheduling. The module was integrated with the Faborg-Sim simulation tool. As a case study, a heating boiler manufacturing system was analyzed and simulated with six products and customers' orders by using production data from the PRGA-Sched module in Faborg-Sim. The results showed that a shorter total completion time is obtained and saved than the initial situation by via PRGA-Sched module.