Abstract: The lack of fit test was introduced to test aptness of some height diameter(H-D) models.The full model and reduced model test were employed to test whether it was reasonable to set some parameter of three-parameter H-D models a fixed value,with the result that two parameter models were enough to describe H-D relationship.With the comparison of six two parameter H-D models,the commonly used power function H=aDb,the hyperbolic function H=aD/(D+b) and the specail case of Richards function suggested by this paper H=a(1-e-0.05D)c gave the most satisfactory results,thus were recommended as the basic H-D models.