Soil fungal communities are crucial for maintaining ecosystem functions, but it remains unclear that how environmental changes such as nitrogen deposition affect their stability. In this study, by using high-throughput sequencing and network analysis, we investigated the effects of different nitrogen addition levels on soil fungal community characteristics for three consecutive years. The connectivity was quantified by calculating ″cohesion″ to predict the stability of fungal networks. The results showed that there was a significant time effect on the response of fungal diversity and community stability to nitrogen addition. Compared to the previous two years, nitrogen addition altered the fungal beta diversity in the third year, and low nitrogen addition significantly increased the Chao1 and Shannon indexes of fungi in the 0-10 cm soil layer. Network analysis revealed that the proportion of positive connections in the fungal network increased and the average clustering coefficient and modularity decreased as the amount of added nitrogen increased. Cohesion analysis showed that high nitrogen addition significantly reduced the absolute value of negative: positive cohesion of fungi in both soil layers in the third year, while low nitrogen addition increased or did not change the ratio. This suggests that high-dose nitrogen addition can affect the ecosystem service function of fungal communities by destroying the stability of fungal communities. This study provides new insights for evaluating the stability of soil fungal communities in forest under different levels of nitrogen deposition, which is of scientific significance for evaluating the ecological effects of nitrogen deposition.