In order to solve the planning and design problems of the microgrid demonstration project, a set of simulation systems for microgrid capacity planning and operation based on Matlab has been developed in this study for the microgrid capacity planning and operation. Different from the traditional implementation of simulation software, the system can support the environment programming of multi-application strategy for the microgrid, and realize the functions of raw data analysis, distributed configuration of power capacity, energy storage system planning, and system operation simulation, etc. It also has high application adaptability and simulation precision. The application result of the Tibet Nyima Microgrid Project shows that the planning simulation system can well simulate the microgrid’s actual running effect, and provide useful analysis as well as calculation for the power planning of microgrid in early stage.