Abstract: The crown coefficient of Platycladus orientalis was studied by image analysis.The empirical formula N=10 000/(0.377H) was established by using average crown coefficient and tree height.Developing a density control table of P.orientalis based on weak competition conditions.Results indicated that the density model from the trees under weak competition was consistent with thinning test at Yanzishan forestry experimental station and existing density models.It also suggested that proper transmittance in non-commercial plantation of P.orientalis was benefit to promote the natural regeneration, maintain the plant diversity and prevent the soil and water loss.