Abstract: To investigate the effects of the IRCC on soil fertility and microorganisms, we compared the effects of different farming time (0 years - Traditional monoculture rice field, TRF; 2 years; 4 years; 6 years; 10 years) on the physicochemical properties, microbial diversity, and carbon metabolism capacity of the soil. The results showed that the IRCC increased the fertility of paddy soil, with higher levels of TC, TN, \rmNO^-_3 -N, \rmNH^+_4 -N, \rmNO^-_2 -N, and AP compared to TRF. In IRCC fields, the nutrient content was higher in TRC than that in PRC. Additionally, the content of TC, TOC, TN, \rmNH^+_4 -N, \rmNO^-_2 -N, and TP increased with longer farming time, while \rmNO^-_3 -N and AP increased and then decreased over time. With extended farming time, no significant differences were observed in soil microbial quantity, but the microbial diversity indices gradually decreased. In PRC, the soil microbes showed a higher ability to utilize carbon sources than compared to TRC, with the order being AWCD_PRC-1>AWCD_TRF>AWCD_PRC-4>AWCD_PRC-6>AWCD_PRC-10 and AWCD_TRC-4>AWCD_TRC-2>AWCD_TRC-6>AWCD_TRC-10. The results indicate that the IRCC mode, with an appropriate farming time, is beneficial for improving paddy soil fertility, enhancing microbial diversity, and increasing carbon utilization capacity. However, long-term IRCC farming (beyond 4 years) has adverse effects on soil fertility and microbial carbon utilization activity. These findings provide a reference for achieving the healthy and sustainable development of ecosystem in the IRCC mode.