Abstract: A structure density diagram is devised for natural schrenk spruce stands in Xingjiang, China, on the basis of the stand density control diagram in accordance with the theory used in Japan. The diagram consists of Y-N curves, equivalent boundary diameter curves and a full density curve. A Y-N curve is derived from the relation between cumulative summation (Y) of individual tree volume, and number (N) of these trees, and expressed by Y=AwN+BN from which we obtain the three-parameter Beta-type distribution function of individual tree volume. With this diagram, not only the total number and volume of a stand, but also the number and volume of trees of the selected diameter can be found. In this respect, it is better than the stand control diagram, but the best way is to use both simultaneously.