Abstract: An accurate description of stem profile curve of the precious tree species in tropical region can help to estimate the tree number and volume of certain species, and thus provides technical support for reasonable bucking. With a total of 120 trees(40 for each species), three species induding Erythrophleum fordii, Castanopsis hystrix and Tectona grandis, were investigated in this research. The tape equations for the three species were developed using the simple taper equation, segmented taper equations and the variable form taper equations respectively. The optimal taper equations for the three tree species were determined through the comparison and analysis of statistical quantities of the index of correlation, the residual sum of squares, the mean prediction error, the variance of prediction errors and the root mean square error. With the optimal taper equation, a preliminary quantitative analysis was carried out on the stem profile variations of the three precious tree species. The results showed that the prediction precision of the taper equations for each species was high. Especially, the segmented taper equations with optimization algorithms were the best. With the optimal equation, the variation tendency of the stem profile of the trees were found as following: the variation of stem profile of T. grandisin in the relative height range of 0 to 0.8 was the largest, followed by E. fordii, and the variation of C. hystrix was the smallest. But in the relative height range of 0.8 to 1, the variation of stem profile of C. hystrix was the largest, while the variation of E. fordii and T. grandis were comparable. Therefore, the segmented taper equations with optimization algorithms is recommended to describe the stem profile of these three tree species in tropical regions, which can be used to estimate the stumpage and timber quantity and to guide reasonable bucking for precious tree species.