In order to realize the high quality and high yield back thinning of large size InSb hybrid chips, a single-point diamond turning technology combined with grinding and polishing process is introduced. This process uses single-point diamond turning technology to remove a large amount of thickness of InSb chip, and on this basis, further remove the turning damage through rotary grinding process. Finally the back of 1280×1024 (25 m) large-size InSb hybrid chip is thinned. The half-peak width of the material surface is about 8.20--11.90 arcsec. Compared with the traditional grinding process, this process has strong compatibility with semiconductor chips with large size and poor surface shape, and solves the problems of high crack rate and uneven thinning thickness caused by surface shape problems of large size chips in the traditional grinding process.