Based on the orthogonal design,two key quality factors FWHM and surface roughness of the Si-based composite substrate were studied by a series of process tests and experiments:MEE epitaxial temperature,MEE annealing temperature,CdTe epitaxy temperature and CdTe annealing temperature impact.The variance analysis of the measured experimental data was carried out by statistical techniques.The results show that the annealing temperature of CdTe is the key factor affecting FWHM.The effect of MEE annealing temperature and CdTe extension temperature on Ra value is significant.The optimal epitaxial process conditions were obtained through this series of experiments.