Molecular beam epitaxy was used to study the growth of CdTe/Si composite substrates on a 4-inch silicon substrate. Optical profilometer, atomic force microscope, Fourier infrared spectrometer and other equipment were used to test the cadmium telluride film. The test and analysis results show that the thickness uniformity, surface roughness, warpage and half-width of the cadmium telluride film meet the expected standards, which can provide a good substrate for the epitaxial mercury cadmium telluride film.