Abstract: Extracellular enzymes are essential for mediating the biogeochemicalcycling of carbon, nitrogen, and phosphorus in wetland sediments, influencing nutrient dynamics and environmental quality. To explore the variations in extracellular enzyme activity in sediments of naturally restored wetlands across different restoration periods and to identify the driving factors, this study was conducted in the Hongze Lake Wetland National Nature Reserve. Sediment samples were collected from wetlands with varying restoration durations (0, 2, 3, 5, and 10 years since restoration). Enzyme activities were measured by fluorescence measurement technology, and sediment chemical properties were analyzed using conventional chemical methods. The results showed that in wetlands restored for 3 years or longer (≥3a), extracellular enzyme activity in the 0-10 cm sediment layer significantly increased compared to degraded wetlands (0 years of restoration, 0 a). In contrast, enzyme activity in sediments of wetland restored for less than 3 years (<3 a) remained relatively unchanged. Additionally, in wetlands restored for 3 years or longer (≥3a), enzymes activities (except for phosphatase) were significantly higher in the surface sediment layer (0-10 cm)than in deeper layers (>10-20 cm and >20-30 cm). Furthermore, enzyme activity in deeper sediments exhibited a lagged response to restoration duration, indicating that surface sediments are more sensitive to restoration-induced changes. During natural restoration of 3 years or longer, the organic matter and total nitrogen content in sediments increased progressively, Correspondingly, enzymes involved in carbon cycling such as cellobiohydrolase (CBH), β-1,4-xylanase (βX) and β-Glucosidase (βG), and phosphatase involved in phosphorus cycling (PHOS), showed increasing trends with restoration time. Among nitrogen (N)-cycling enzymes, N-acetyl-β-D-glucosaminidase (NAG) activity increased, while leucine aminopeptidase (LAP) activity remained stable between 5 and 10 years of restoration. Except for phosphatase, all measured enzymes exhibited higher activity in surface sediments (0-10 cm) compared to deeper layers, highlighting the stratification of microbial and enzymatic processes in sediment profiles. Correlation analysis revealed that in wetlands restored for 3 years or longer, the activities of carbon- and nitrogen-transforming enzyme (CBH, βX, βG, NAG, and LAP) were significantly correlated with sediment properties, including organic matter, total nitrogen, total phosphorus, available phosphorus, and pH. However, in wetlands restored for 10 years, phosphatase activity showed no significant correlation with organic matter, total nitrogen, total phosphorus, or available phosphorus, suggesting that phosphorus cycling may become less dependent on sediment nutrient status in long-term restored wetlands. These findings indicate that wetland restoration enhances sediment enzyme activity and promotes the accumulation of organic matter and total nitrogen, thereby facilitating carbon and nitrogen sequestration in sediments.