In order to explore the effects of Dicranopteris dichotoma on the monthly dynamics and turnover of soil microbial biomass carbon and nitrogen in the restoration process of Pinus massoniana forest in eroded degraded red soil, the P. massoniana forests with different restoration years were used as the research object. The contents of soil microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN), turnover rate, turnover time and flux in the soil of 12 months in the soil of P. massoniana forest with D. dichotoma, removal of D. dichotoma and bare land were compared and analyzed, and their relationships with soil physical and chemical properties were analyzed. The results showed that : (1) The average content of MBC and MBN in the treatment of retaining D. dichotoma was 26.99%~277.31% and 13.54%~173.39% higher than that in the bare land, while the distribution of the treatment of removing D. dichotoma was 12.29%~27.01% and 5.02%~28.45% lower than that of retaining D. dichotoma. (2) The seasonal dynamics of soil microbial biomass carbon and nitrogen in all treatments showed a trend of higher in spring and summer and lower in autumn and winter, the soil microbial biomass carbon and nitrogen content before entering the growing season can better reflect the average level of the region; (3) In the restoration process of degraded P. massoniana forest, D. dichotoma coverage decreased soil microbial biomass carbon and nitrogen turnover rate, increased turnover time, increased soil microbial biomass carbon and nitrogen content and flux, and promoted soil organic matter accumulation and nutrient release. Correlation analysis and stepwise regression analysis showed that MBC and MBN flux were significantly positively correlated with DOC and DON, respectively, and turnover rate was significantly negatively correlated with NH₄⁺-N and TN, respectively, indicating that soil carbon and nitrogen and their availability were key factors affecting soil microbial biomass turnover.