The influence of clear cutting Chinese fir plantation on the characteristics of runoff water chemistry are studied to explore the capability of Chinese fir plantation of regulating, accumulating and conserving soil nutrients. Periodically sampled runoff from the ditch below the catchment area before and after clear cutting and analysed nutrient quantities of runoff sampled, the differences between nutrient quantities of runoff before clear cutting and those after clear cutting are the increments of forest land nutrient loss caused by clear cutting Chinese fir plantation. Experiments continued for 5 years,the results show that the clear cutting Chinese fir plantation results in soil nutrients running off in great quantity. In two years after clear cutting, the running off increments of N,P,base cation (K+,Na+,Ca2+,Mg2+) and dissolvable salts are 0.54kg/hm2,0.817kg/hm2,42.67kg/hm2,774.44kg/hm2 separately. The results indicate that Chinese fir plantation has a fair capability of regulating, accumulating and conserving soil nutrients.