Abstract: By setting up the lumped parameter mathematic models of HTGR helium gas turbine and compressor device,and using Matlab/Simulink to build the simulation models,the transient operation characteristics of startup process of helium gas turbine were studied.The simulation results give the operation curves for high pressure compressor,low pressure compressor,and some key curves of compressor outlet pressure,core inlet and outlet temperature,turbine power,compressor power and generator power changing with core power.The calculation results show that,in the startup process,the trends of these main parameter curves meet the design requirements,and the transient characteristics simulation results are reasonable.