The influences of different polishing methods (mechanical, chemical etching method or chemical/mechanical) on the characteristics of Pb1-xGexTe thin films deposited on Si substrate were studied. It is found that Pb1-xGexTe thin films deposited on Si substrates which are polished by chemical/mechanical polishing (SiO2 or Cr^＋ colloid) have a denser structure and flat interface, and they have also a deposition rate of 7% or 18% greater than those deposited on the surfaces of Si substrates polished by chemical etching for the directions of 〈 111 〉 and 〈 100 〉, respectively. Moreover, this thin film has a higher refractive index than those deposited on the surfaces of Si substrates polished by chemical etching, and the refractive index increases with the decrease of temperature. At low temperature, the refractive index increases with the increasing of wavelength. The change of refractive index for the substrates polished by chemical etching is greater than that for the substrates polished by chemical/mechanical one. The crystal structure, composition and element depth-profile of Pb1-xGexTe thin film remain unchanged after surface is polished by mechanical polishing, while optical transmission of this thin film is increased, and extinction coefficient and refractive index are decreased.