To investigate the response of subtropical forests to increased nitrogen deposition, a field experiment was conducted in a 12-year-old Chinese fir (Cunninghamia lanceolata) plantation exposed to four N treatments designated as N0 (control), N1, N2 and N3 at the doses of 0, 60, 120 kg N hm-2 a-1 and 240 kg N hm-2 a-1, respectively. Each treatment comprised three replicate plots of 20 m×20 m which were sprayed with urea on the forest floor at the beginning of each month, lasting from January 2005 to December 2006. Litter bags were randomly placed on the forest floor and collected bimonthly, and litter was analyzed for mass remaining, carbon and nitrogen content. Based on two years of litterbag collection and analyses, the average carbon contents in the decomposing litter collected bimonthly were estimated at 4647%, 46.35%, 46.79% and 46.6%, respectively, for N0, N1, N2, and N3, showing no significant difference between treatments but decreasing with time consistently. The concentrations of nitrogen in leaf litter were found to increase significantly with the doses of nitrogen additions. For the above four treatments, the decomposition coefficients determined by Olson equation were respectively 0739, 0.744, 0.936 and 0.708, with turnover time of 4.26, 4.26 , 3.46 and 4.41 years, for C element; the decomposition coefficients were 0.458, 0.543, 0.776 and 0.565, with turnover time of 6.26, 5.44 , 3.91 and 5.20 years for N element. N1 treatment stimulated N release from the litter, but produced no effects on C release; N2 accelerated release of both C and N, but N3 exhibited inhibitory effects to some extent. The N1, N2 and N3 treatments decreased C/N ratios in leaf litter by 8.59%, 14.20% and 17.54%, respectively.