The main purpose of this study is to apply machine vision to the growth of sapphire crystal, the image of sapphire crystal neck and molten convection line can be achieved with CCD and the image processing software developed by myself, in the sapphire crystal growing furnace, temperature is up to more than 2000 degrees. The operator must be observing the crystal growing situation for a long time to get the best seeding time, but high temperature and brightness of the furnace will affect the judgment of the operator. By developing a machine vision software to automatically determine the crystal growth seeding conditions in the furnace to get the best result of crystal growth.