This paper analyzed the calculation principle and applicable scope of tree volume by Pressler method,and attempted to use the tree height method instead of Pressler method due to the potential ob-struction of the height observation point and the low efficiency of the observation.Therefore,based on the study of the form quotient(q)and shape index(r)using effective data from existing analytical wood,the method for directly calculating the Pressler function(B)was proposed,which solved the problem of diffi-culty and low efficiency in measuring Pressler height(hR).