A field simulated experiment was conducted to study the effects of nitrogen deposition on the fine root decomposition and related nutrient release of Picea schrenkiana var.tianshanica.Four treatments were designed as CK(control,Non-addition nitrogen),LN(Low nitrogen,5 kg·hm^-2·a^-1),MN(Mid nitrogen,10 kg·hm^-2·a^-1) and HN(High nitrogen,15 kg·hm^-2·a^-1).The results showed that:(1)After two years decomposition,the fine root remaining percentage of P.schrenkiana var.tianshanica ranked as HN(74.044%),MN(71.967%),CK(68.156%),LN(61.933%),and the difference was significant in four treatments.(2)The rule of monthly decomposition rate in former stage was not obvious under four treatments,while it was CK>MN>LN>HN in final stage.(3)The required time to fine root decomposition 50% ranked as LN(3.31a),CK(3.67a),MN(4.28a),HN(4.64a),while it was 14.39a(LN),15.93a(CK),18.58a(MN) and 20.17a(HN) for decomposition 95%.(4)The transfer model for C in fine root was direct releasing,while it was riching-releasing model for N.(5)The relationships between fine root decomposition rate and C concentration in fine root were negative linear correlation in four treatments;the relationships between fine root decomposition rate and N concentration were negative linear correlation in CK and LN.The decomposition rate was increased first and decreased then as the N concentration increasing in MN and HN.