Abstract:In the stem form curve formula of Pinus tabulaeformis y=[a0xa1-a2+a3/(a4-x)]0.5, three conditions must be satisfied: (1)a4 is given value beyond the range 0～H, H stands for the tree height; (2) -a2=-a3/a4;(3) The value of expression within radical sign must be positive on any point of the tree stem. Fitting curve based on 129 P.tabulaeformis trees leads to the results: Sharing 89.9% at the condition of R2>0.98, the absolute value of systematic error <3% coves 79.1%,and the absolute value of systematic error is less than 7% at the most. Comparing the tree stem valume derived form formula of stem form curve of the one derived from sectional measurement by means of Smalin‘s formula, the absolute values of error are not more than 4%, where below 1% shares 76.7% of sample trees. The systematic error of 129 trees is 0.53%. The proposed formula of stem form curve in this paper can reflect the stem form profile of P.tabulaeformis very suitablely.