Abstract: This paper used different weighting function to regress the tree height-diameter curve equation of Pinus kesiya var.langbianensis with heteroscedasticity,and selected the optimal weighting function form.According to previous research results,the article proposed a set of variable-weighting function theory,and researched on different heteroscedasticity of group data by variable-weighting function.Study results show that the heteroscedasticity strength in model can be expressed by variance linear slope,and the heteroscedasticity strength in equation will affect the choice of weighting function.

Key words: tree height-diameter curve, heteroscedasticity, weighting function, variable-weighting function, variance linear slope method