Abstract: 23 soil factors in the different sites (site-index 12,14,16) and different growth periods (young, half-mature and mature) of the first and second generation Chinese fir plantations in Dagang Mountain, Fenyi County of Jiangxi Province,were determined.By the method of PCA, three synthesized factors were selected as targets on evaluating soil fertility in Chinese fir plantation. The results were quantified, scored and sequenced to the data-collected relevant to the soil fertility in the selected plots using PCA.The result showed that the score of all the 2nd generation Chinese fir plantations were much lower than that of the 1st generation. It revealed the fact that soil degradation existed in successive Chinese fir plantations. The result also showed the tendency of soil productivity of different growth period of 1st rotation was that the soil productivity decreased from young to half-matured period, but raised slightly from half-matured to matured period, this meaned that 1st rotation was the latent period of soil degradation of Chinese fir plantation.