A N addition experiment was established with four treatments: control (no fertilization), low-N (20 kgN/(hm²·a)), medium-N (50 kgN/(hm²·a)) and high-N fertilization (100 kgN/(hm²·a)) in an N-limited Pinus sylvestris forest in Hebei Province, North China to study the production, biomass and turnover of fine root systematically. The results showed that fine root productivity (NPPfr) increased in low-N plots, decreased in high-N treatment, while the proportion of NPPfr to net primary productivity (NPP) reduced in low-N addition and increased in medium-N addition. With the increase of N availability, root biomass decreased, turnover rate increased, and carbon returned to soil decreased at first and increased later. The influence of N availability on NPPfr didn’t change with depth, while turnover rate varied among depth. N-addition made an impact on fine root productivity through soil nitrogen content, soil carbon content and soil pH, while affecting turnover rate of fine root by root carbon and nitrogen content.