To research the steady control law and altitude, atmosphere characteristics of micro-turbine generator(short for MGT), the simulation model of its performance calculation was built, and compute programs was compiled. Through simulating and calculating of certain MGT, the control laws of its maximum state, throttle state and idle state were obtained, altitude and atmosphere characteristics were calculated and analized. Compared with the testing data, it indicated that the simulation results were reasonable and appliable, and could provide some theoretic guidance to the characteristics anticipation and test of MGT.