Abstract: The data of crow width and DBH for more than 500 stems above average tree pertaining to about one hundred temporary sample plots(area 200—500m)of different stand types are collected.Significance of difference among stand types are tested.Results of investigation indicates that relation between DBH and crown width is not effected the age of stand,stand-density and site condition.Thus:C_w=D/2.397+0.00254×D R=0.99 S=±0.15 The empirical equation of DBH and maximum stand density has been found as:N=25.95+23,961.17×D^-1 R=0.99 S=±37 Through trials of stationary thining experiments,a guide of optimum density for managing Larch plantation has been developed,which can be used as the technical criterion for controlling thinning intensity in practical use. The application of this guide and its effects are also described.