InSb crystal is an important material for medium wave infrared detector fabrication. To satisfy the development needs of a new generation of ultra-large-scale array infrared focal plane detectors, the growth of large size InSb crystals is studied. The key technologies for large size crystal growth are solved, 4 inch high-quality InSb single crystals are grown successfully and high-quality 4 inch polished InSb wafers are fabricated. The test results show that the length of the crystal with a diameter greater than 120 mm is longer than 100 mm. The dislocation density of the crystal is less than 100 cm^-2. Its electric parameters, carrier concentration and carrier mobility are conformed to the requirements for producing high performance large format infrared focal plane detectors. This lays a good material foundation for the development of a new generation of ultra-large-scale array infrared focal plane detectors.