Abstract: The simulation system is based on the network environment. And it is intended to analyze and calculate the physical process of the reactor core, the main loop system and steam generator, etc., as well as to simulate the normal operation and transient accidents. The simulation results are displayed in graphical user interface dynamically. The system can be used as an educational tool to understand the design and operational characteristics of HTR-10, and can also provide online supports for operators in the main control room.