To formulate safe， high quality and efficient polyculture technical specifications and explore sustainable development of aquaculture technology， a comparative experiment of three co-culture modes， including experimental group （rice-crab， RC； rice-crayfish-crab， RCC） and control group （intensive crab， IC）， was set up in Suzhou， Anhui Province. By comparing and analyzing the N and P balance， N and P utilization， biomass and diversity of plankton and eco-economic benefits of the three modes， the advantages of rice-fish polyculture and the best rice-crab co-culture mode were explored. The results showed that the content of N and P in the substrate increased in all three culture modes， and the most significant increase was in the IC mode （P<0.05）. The N and P balance showed surplus in all patterns， the N surplus in IC， RC and RCC modes were 1 030.92 kg/hm²， 364.37 kg/hm² and 188.75 kg/hm²， and the P surplus were 171.35 kg/hm²， 81.67 kg/hm² and 76.96 kg/hm²， respectively. The N utilization rate in IC， RC and RCC modes were 16.47%， 48.98% and 65.71%， and the P utilization rate were 7.61%， 18.22% and 24.29%， respectively. Compared with IC and RC modes， the total amount and increase of phytoplankton species and the Shannon-Wiener diversity index were the highest in the RCC mode. The economic benefit of RC and RCC were 22.78% and 4.48% lower than those of IC， respectively. The economic benefit of RCC was not significant different from that of IC. In conclusion， compared with the intensive cultivation mode， the rice-fish co-culture pattern is more friendly to the ecological environment， while RCC has better economic benefits than RC.