Abstract: The study aims to ascertain the effect of soil Nitrogen (N), phosphorus (P) and potassium (K) on tannin content of gallnuts in different growth periods. Research on gallnuts could not only improve the tannin content, but also guide farmer’ s production practice. Spectrophotometric method was adopted to measure tannin content of gallnut, branches, leaves and the gallnut physical characteristics, soil available nutrient factor in different growth periods on Rhus chinensis Mill in Zhangjiajie main gallnut producing areas. With the application of statistical methods such as correlation analysis and stepwise regression analysis, the author explored the relationship between tannin content of gallnut in different growth periods and the above indexes. Results showed that, for gallnut in the growing period on Rhus chinensis Mill, tannin content and its dry weight were positively correlated (P=0.000＜0.01); for gallnut in the mature stage, the tannin content was correlated with dry weight, and had a significantly positive correlation with gallnut inclusions, its significance was P= 0.000＜0.01. At the same time, in different growth periods, there were significant differences between soil nutrients and tannin content accumulation in gallnut. In the growth stage, the soil nutrient nitrogen and phosphorus and the tannin content had the correlation coefficients of 0.628 and 0.646, respectively; but in mature stage, their correlation coefficients were - 0.473 and 0.420. So, the soil nutrient factor was one of the important ecological factors that affecting the tannin content accumulation of gallnuts on Rhus chinensis Mill.