Rice-crab co-culture(RC) is an integrated cropping-culture pattern that combines rice and aquaculture production by using the theories of interspecific mutualism, food chain, and ecological niche, it is important for advancing the development of agro-ecology. Spiders are important predatory natural enemies in rice fields, to find out the environmental niche characteristics of major spiders in RC system, this study investigated the species and quantity of major spiders in the conventional rice fields and rice-crab co-culture fields on temporal and spatial scales and analyzed the niche width and overlap of spiders by using the niche theory. The results showed that: (1) 892 spiders belonging to 30 species of 10 families were investigated in the rice fields. The proportion of spiders in RC fields was 57.96%, 15.92% more than in conventional rice fields. The numbers of Lycosidae, Linyphiidae, and Tetragnathidae in the two treated fields ranked in the top three, and the number of Lycosidae was the highest, with 18.60±1.17 (the conventional rice fields) and 26.00±2.39 (RC rice fields), respectively. (2) In the temporal dimension, the niche width of Lycosidae, Linyphiidae, and Salticidae increased, while that of Tetragnathidae decreased in the RC system. In the spatial dimension, the niche width of Lycosidae, Linyphiidae, and Tetragnathidae increased, while those of Clubionidae decreased in the RC system. From the perspective of temporal-spatial dimensions, the niche width of Lycosidae and Linyphiidae increased significantly by 49.64% and 47.49%, respectively, while that of Clubionidae decreased by 25.04%. (3) The temporal-spatial niche overlap index and niche proportional similarity index of most spiders increased or remained the same in the RC system, however, the index of Clubionidae to Araneidae and Clubionidae to Tetragnathidae decreased. In this study, we first analyzed the ecological niche characteristics of major spiders in the rice-crab cropping system. Rice-crab co-cropping changed the spatial and temporal environmental niches, overlapping ecological niches, and similar ecological niches of spiders to varying degrees by affecting the intensity of spider activity, distribution pattern, and population structure in the paddy field environment. When competition intensified, spiders increased the utilization of more resource sequences to improve insect control. Rice-crab co-culture not only increased the number of spiders, but also changed the degree of spiders' utilization of temporal and spatial resources, resulting in a higher level of resource utilization, a more even distribution, and a longer period of occurrence, and facilitating spiders to perform their pest control role better. This study provides basic data for the study of spider ecological niche in rice-crab fields.