A new method was studied of controlling drying process of taking critical moisture content gradient and critical tensile strain before wood surface checks as a target. The drying technology of C. carlesii Hay and C. fargesii Franch had been tested in air kiln. A low, middle temperature and high humidity drying schedule had been advanced. It can efficiently dry C. carlesii Hay and C. fargesii wood. The result provides a method for making drying schedule and a basis for a controlling method of wood kiln drying.