Water regime changes caused by natural and anthropogenic activities can significantly affect soil carbon cycle in wetland ecosystem. Some fishery activities could greatly impact on wetland water regime, but, till now, their influences on wetland soil carbon cycle are still not fully understood. In this paper, we investigated the effects of the dike of Lake Dahuchi, which was used to restrain the fish at the low water period, on soil carbon cycle in the littoral wetland. Our results showed that soil total organic carbon (TOC) was not changed by the dike, but soil light fraction of organic carbon inside the dike was significantly lower than that outside the dike by 35.03%. Meanwhile, the littoral wetland soil inside the dike had higher soil organic carbon (SOC) mineralization rate, but lower temperature sensitivity. The Q₁₀ of SOC mineralization inside and outside the dike were 2.72 and 2.85, respectively. The dike did not significantly change the moisture sensitivity of SOC mineralization. In addition, the determining factors of SOC mineralization rates inside and outside the dike were dissolved organic carbon and light fraction of total nitrogen, respectively. In summary, soil carbon cycle in littoral wetland in Poyang Lake could be modified by fishery activities. Scientists should take account of the effects of fishery in simulating soil carbon cycle of the wetland ecosystem in future.