Software requirements change frequently, which pose many threats to software projects. Effective management of requirements change determines the success or failure of the software project. System dynamics can be used to simulate the process of software requirements change management, aiming to dynamically analyze and predict the cause of requirements change and the effects of change on software projects. System dynamics also can assist software organizations to improve requirement change management processes. In this study, the system dynamics method is first used to model the process of open source software requirements change management which refers to the agile processes. Then, the models are tested to find out the errors and correct them. Next, taking the Spring Framework as an empirical case study, the system dynamics simulation of the software requirement changes management process of the project 3.2.x branch is carried out. According to the simulation results, the improvement of the requirement change management processes is simulated. By comparing the baseline simulation results with the improvement simulation results, it shows that all the improvements effectively reduce the software defect rate and improve the software quality. In addition, based on the cost and schedule of the software project, the process improvement suggestions are provided.