Abstract: The nitrogen deposition affects the releasing process of soil carbon, nitrogen and phosphorus nutrients by regulating the soil extracellular enzyme activity. Although the studies have focused on the response of soil extracellular enzyme activity and its stoichiometric ratio to nitrogen addition, the effects of long-term (> 10 years) nitrogen addition remained unclear. Based on the 11-year field nitrogen addition experimental plot, the subtropical evergreen broad-leaved forest was taken as the research object, and the changes of soil extracellular enzyme activities β-1,4-glucosidase (BG), β-1,4-N-acetyl-glucosaminidase (NAG), acid phosphatase (AP), leucine aminopeptidase (LAP) and their stoichiometric ratios BG/AP, BG/(NAG + LAP), (NAG + LAP)/AP in different soil depths (0-10 cm, 10-20 cm, 40-60 cm, and 80-100 cm) under three nitrogen addition levels control (CK, 0 kg·hm⁻²), low nitrogen (LN, 40 kg·hm⁻²), high nitrogen (HN, 80 kg·hm⁻²) were investigated to reveal the microbial nutrient limitations and their response mechanisms in different soil depths under different nitrogen application levels. The results showed that: (1) The soil available phosphorus (aP), nitrate nitrogen (NO₃⁻-N) and mineral nitrogen (AN) contents decreased with soil depth, while HN treatment significantly increased the nitrate nitrogen (NO₃⁻-N) and mineral nitrogen (AN) contents. (2) HN treatment significantly increased the soil BG, NAG and LAP activities, and the interaction between nitrogen addition and soil layer significantly affected the soil AP activity. In the 0−10 cm soil layer, the soil AP activity after LN treatment was significantly higher than that of CK treatment and HN treatment, while there was no significant difference in the remaining soil layers under the nitrogen addition level. (3) (NAG + LAP)/AP and BG/AP ratios increased with the increase of soil layer and were not affected by the nitrogen application level, while LN treatment significantly reduced BG/AP and (NAG + LAP)/AP ratios. (4) The soil microbial carbon limitation increased with the deepening of soil layer, while LN treatment alleviated the soil microbial carbon limitation. However, there was microbial nitrogen limitation under the three nitrogen addition levels. The LN treatment significantly reduced the microbial nitrogen limitation in the 0-10 cm soil layer, but the deepening of the soil layer would aggravate the soil microbial nitrogen limitation. (5) The vector angle (VA) was positively correlated with the soil carbon-nitrogen ratio (Soil C/N), soil carbon-phosphorus ratio (Soil C/P), total carbon (TC), total nitrogen (TN), total phosphorus (TP), mineral nitrogen (AN) and available phosphorus (aP). The vector length (VL) was positively correlated with BG/(NAG + LAP), (NAG + LAP)/AP, BG/AP, soil water content (SWC) and pH. The long-term nitrogen addition increased the soil nitrogen availability and alleviated the microbial carbon limitation in surface soil. However, the microbial nitrogen limitation has always existed, and with the increase of soil depth, the soil nutrient limitation was stronger. This study clarified the vertical differentiation characteristics of microbial nutrient limitation under long-term nitrogen deposition and their driving mechanism, which provided a scientific basis for predicting the response of forest ecosystem nutrient cycling to global change.