Rice-crayfish co-culture system is a successful model of the coupling development of green rice and green aquatic products.The field distribution characteristics of crayfish in high-frequency distribution sampling area （GP），low-frequency distribution sampling area （DP） and none-crayfish control area （CK） were studied with cage capture method to explore the symbiotic mechanism of rice and crayfish.The soil properties，diseases，pests and weeds in rice field and the yield of rice were investigated to study the ecological effects of rice-crayfish co-culture system.The results showed that there was a significant positive correlation between the distribution quantity of crayfish in paddy field and the water depth，with the univariate linear regression equation of y=197.69x-25.77.The high frequency distribution of crayfish improved the soil structure，significantly reduced the soil bulk density of 0-10 cm by 6.25%-11.76%，and significantly increased the total capillary porosity of 0-10 cm soil layer by 8.08%-10.78% （P<0.05）.The high frequency distribution of crayfish significantly increased the content of organic matter in 0-10 cm soil by 6.24%-10.30% and the microbial biomass carbon in 0-20 cm soil layer （P<0.05），and significantly inhibited the growth of weeds.Different distribution frequencies of crayfish had no significant impacts on diseases and pests，yield and yield components of rice，but the yield tended to increase with the increase of distribution frequency.Therefore，different distribution frequencies （water depth） of crayfish can be properly distinguished by management and studied in terms of production and scientific research to promote the green and sustainable development of ecological planting and breeding of rice and crayfish.