The recent results on molecular beam epitaxy growth of HgCdTe on Si composite substrate are reported.Through the use of on-line measurements such as RHEED and Pyrometry,we found and optimized the temperature ramp-rate profile for growth of HgCdTe on 3-inch Si substrate.Through the growth of secondary CdTe-buffer,the strain was decreased.The FWHM and EPD of HgCdTe wafer are about 90.72arcsec and 1×107 cm-2 at the thick of 8 μm respectively.On that wafer,we have fabricated 1280×1024 high quality MW FPAs.