Abstract: The one-dimension flow and heat transfer models are built to simulate the components of helium turbine system,including the helium turbine model,compressor model,heat exchanger model,valve model,pipe model and shaft velocity model.The transient simulation code is established in MATLAB.The accident of loss of load and the transient of decreasing heat transfer capacity of the main heat exchanger by 5% are simulated,and important parameters like helium flow rate,temperature,shaft velocity,power rate and compressor surge margin are analyzed.The calculated results agree with the analyzed results.This shows that the present model can be used to simulate the dynamic process of helium turbine closed-cycle system.