In this paper,we arranged a field experiment of N addition for the plantation of Atriplex canescens in Xidatan,Pingluo County,Ningxia Province.Based on the data of leaf C,N and P concentrations collecting in different seasons,we mainly explored the seasonal dynamics of leaf C∶N,C∶P and N∶P ratios of A.canescens,and their responses to N addition.We also discussed the correlation between leaf C∶N,C∶P and N∶P with leaf nutrient resorption.The results showed that:(1)During whole growing season,leaf C,N,P concentrations were higher in August and September but lower in June and November,whereas leaf C∶N,C∶P and N∶P ratios showed contrary trends;(2)N addition increased N concentration and N∶P ratio in green leaves,decreased C∶N ratio in green leaves,leaf N resorption proficiency (NRP) and P resorption proficiency (PRP),but had not clear effects on C concentration in green leaves,P concentration in green leaves,C∶P ratio in green leaves,leaf N resorption efficiency (NRE) and P resorption efficiency (PRE)；(3)Both NRE and NRP had positive correlations with C∶N ratio in senescing leaves.PRE positively correlated with P concentration in green leaves,but negatively correlated with that in senescing leaves.PRP positively correlated with P concentration in green leaves and C∶N∶P in senescing leaves,respectively,but negatively correlated with C concentration in senescing leaves.The above results suggest that,N addition accelerates N uptake in green leaves,reduces the ability of N and P resorption from senescing leaves,consequently improves decomposition quality of senescing leaves.Thus,future increase in atmospheric N deposition will alter plant N strategies in the way of N uptake,N distribution and N transfer,accelerate N release in senescing leaves,further have a direct effect on N cycling process and indirect effects on C and P cycling in plant-soil system.