Abstract: Density Control Diagrams of five site classes of Chinese fir have been corstructed separately. Basic data were collected from 867 sample plots located in 7 Provinces in South China.The relationship between the age and height of a stand is expressed as: H = b0+b1 + b2A2. The model showing the relationship between age, density andmean diameter is D = a + b lg(×100). The latter is applicable to stands aged from5 to 40 years and a density of 1,600 to 6,000 trees per hectare.Diameter lines and stand volume lines are presented’ in the graphs as the main lines, while the full-stocking lines (Nmax. ) and crown width lines (Nc) are demonstrated as reference lines.In practice, these diagrams can be used in the estimation and predication of the mean diameter and yield of a stand.