AbstractDuring decomposition of plant litter, it remains unclear whether carbon (C) and nitrogen (N) are released at similar proportional rates, which hinders our prediction of soil C and N dynamics under the context of global changes. Here, we investigated the relationships between C and N release and their responses to N addition (5 g N m−2 yr−1) to better understand this question. Litter gross N release and immobilization were differentiated by the 15N‐labeling technique. Results showed that the linear relationship between gross N release and C release followed the 1:1 line during the first year but then deviated above the 1:1 line for three types of the four studied litters. Nitrogen addition did not change this relationship, showing an inhibition effect on both C and N releases from the N‐rich foliar litter at the later stage. The inhibition effect of N addition was not found in the N‐poor twig litter, indicating that initial litter N interacted with deposited N to affect litter N release. We propose a novel conceptual model to describe that under N addition, the decrease in gross N release caused a decline in net N release from N‐rich litter, while a decline in net N release from N‐poor litter was due to the increase in gross N immobilization. These findings point to the importance of differentiating the gross N release and immobilization processes for understanding the response of litter N cycling to increasing N deposition and the relationships between C and N release during different stages of litter decomposition.