Abstract: Objected with Chinese fir planted  widely in South China recently, using the sandculture indoor simulation pots supplying with three different P levels, which were 0 mg/kg, 6 mg/kg and 12 mg/kg of KH2PO4 respectively, a competition between neighbor trees environment for P was constructed. Main results were as follows. The treatment of competition for low P could obviously promote the height growth of seedlings of Chinese fir, but P deficiency under competition stress inhibited the growth. Effects of all treatments with different supplying P levels and whether competition or not on root collar diameter growth of Chinese fir were not significant, but the synergistic effect on the ground diameter growth had a certain influence.Increments of all the roots morphological indexes, including length, surface area, diameter and volume, were large under competition for low P.