Vacuum drying of hard wood has been tested and after repeated tests, a method of surface-cooling which can effectively prevent the crack of wood has been arrived at. The paper focuses the discussion on the mechanisms of shortening drying time in vacuum drying and preventing cracks in surface-cooling. The test resutls show that the method of intermitent vacuum drying with an additional surface-cooling process, can not only greatly shorten drying time but also effectively prevent wood cracks, so it is a good method to solve the crack problem long existing in hard wood drying.