Background and aims <p>Net nitrogen mineralization (net N_min) is crucial for soil nitrogen (N) availability and grassland productivity. However, the response of soil net N_min and its seasonal variation to alpine grassland degradation are not fully studied, and key environmental factors and their effects on soil net N_min were also less known.</p> Methods <p>We conducted an in-situ experiment in differently degraded meadows during growing season, including non-degraded meadow (NDM), lightly degraded meadow (LDM), moderately degraded meadow (MDM), and heavily degraded meadow (HDM) to investigate how meadow degradation affects soil net N_min in the Zoige Basin, China.</p> Results <p>Compared with NDM, soil net N_min rate decreased by 29.7%–183.5% by lowering nitrification in degraded meadows due to the disturbance (nibbling and trampling) of livestock and pika; seasonal variations of soil net N_min increased in LDM and HDM, while that in MDM decreased; soil mineral N supply capacity declined in MDM and HDM. The main environmental regulators of soil net N_min varied in different meadows. Low temperature dominated soil net N_min by regulating enzyme activity and bacterial abundance in NDM. The decreased soil TN, tight soil, and reduced vegetation coverage weakened soil net N_min in LDM, MDM, and HDM respectively, which were mainly driven by poor microbial properties.</p> Conclusions <p>These findings highlight meadow degradation reduced soil net N_min and its seasonal variations owing to the changes in regulation pathways of temperature and microbial properties. Applying chemical N fertilizer to improve soil N supply during the regreen stage is key to restoring degraded meadows.</p>