Abstract: The sputtering yield of the silicon thin film by He ions and Ar ions under various parameters (ion energy,angle of incidences) is calculated by Monte Carlo method.The dependences of the sputtering yield on incident ion energy,incident angle and the number of ion are predicted.The simulation results are analyzed.When the number of ion is 2000,ion energy is 3 keV,angle of incidence is 84°,the He ions will appear to the biggest sputtering yield that is 1.30 Atoms/ion;when angle of incidence is 78°,the Ar ions will appear to the biggest sputtering yield that is 8.91 Atoms/ion.