Abstract: A new round state-wide rice-based aquaculture has been carrying out in China during the past 5 years. To improve the total productivity of improved traditional rice- fish co- culture system, the effect of transplanting density and application rate of compound fertilizer (N:P:K=14:2:7) were studied in a field experiment. And based on the field experimental results and environmental consideration, an optimized technology was suggested for rice-fish co-culture. Based on yield analysis from two different filed experiments, a rice hill density with 25 cm both between rows and hills would increase rice yield significantly (P=0.005) without any negative impact on fish production (P=0.175) if fish yield was targeted at 750 kg/hm². The dependency of rice yield to compound fertilizer decreased in rice-fish co-culture system. The yield of both rice and fish had no significant change when the compound fertilizer application rate reduced from 750 kg/hm² to 600 kg/hm². An optimized technology system with best resource utilization and without any environmental risk was innovatively established and the suggestions are as follows: 55±3 g sized krill density (9000 individuals/hm²), rice hill density with 30 cm both between rows and between hills, compound fertilizer application rate 480 kg/hm², predicted fish yield 1500 kg/hm², predicted rice grain yield 7500 kg/hm². The suggested technology could be introduced to whole Qingtian County, where the Globally Important Agricultural Heritage Systems (GIAHS) located in, and other eco-socially-similar regions with essential trials.