Abstract: In order to improve management level of Pinus massoniana forest, the author designs a management-calculation diagram, which is a improvement on the old stand density diagram. Because of the equivalent height curve and equivalent diameter curve replaced by two parallel graduated lines the new techniques adopted in the preparation of the diagram makes its structure simpler than that of the old stand density diagram. It provides a new way for timber cruise, estimation of growth and afforestation design. Its precision is high enough to meet the user's requirements of productive units.