To explore the optimal breeding density of exclusive crabseed for out-season crab at lunar June （Eriocheir sinensis）， this study took juvenile crab as the test object， and set 4 density groups： D1 10 ind./m²， D2 20 ind./m²， D3 30 ind./m² and D4 40 ind./m². The growth performance and culture benefit of each density group were compared and analyzed by pond culture experiment. Results indicated： （1） With the increase of culture density， the average body mass of crabs in group D1 was significantly higher than that in the other three groups during culture. In terms of weight gain rate and specific growth rate， group D1 always had an advantage over the other groups from July to October， but was significantly lower than the other groups from October to November. （2） D3 group achieved the best breeding effect， which was reflected in relatively impressive size and yield， and achieved the highest survival rate， the lowest early maturing rate and feed coefficient. （3） In terms of size distribution， the final size of buckled crabs in groups D1 and D2 was mainly concentrated in the range of 35-45 g， and the weight of buckled crabs in groups D3 and D4 was mainly concentrated in the range of 25-35 g. With the increase of stocking density， the proportion of juvenile crabs in each density group less than 35 g gradually increased， while the proportion of juvenile crabs greater than 35 g gradually decreased. （4） In terms of economic benefits， D4 group achieved the highest income and profit， while D3 group achieved the highest return-on-investment. According to the comprehensive evaluation， the breeding density model of 30 ind./m² can obtain relatively considerable yield and feed coefficient， and its harvest size is also larger， which is the optimal breeding density of June yellow large size crab species.