As a standard software used by NASA of USA, Sinda/G and Nevada are successfully used in the field of space target heat radiation analysis. The target with spherical surface is modeled by FEMAP of Sinda/G lite. Its orbit parameters is setup by Nevada. The simulation is executed by combination of Sinda/G and Nevada. The simulation results show that the heat balance is achieved within 10 minutes. While the target fly on its orbit, there are rapid changing of temperature and its distribution of target surface.