Big-eye mandarinfish Sirdperca kneri is a commercially valued species that naturally lives in the Pearl River water system and the Yangtse River upriver water system. In order to study the reproductive biology of S. kneri, 322 mature individuals captured from the Pearl River water system were measured. By means of biological survey and experimental ecology, the annual change of development of gonad and gonadosomatic index （GSI）, the percentage of gonadal maturity and the fecundity of this fish were determined. And the whole process of embryonic development was observed and photographs were taken continuously. Based on the annual change of gonadosomatic index （GSI） and percentage of gonadal maturity in whole year, it was concluded that the reproductive season of the S. kneri was from April to August, with a busy season from May to June. The individual absolute fecundity ranged from 11 036 to 106 022 eggs, increasing with the body length and body weight and age increased. But the individual relative fecundity did not change even if the body length, body weight or age changing, and kept the level of 100 eggs per gram or so. The eggs of the fish was buoyant and the diameter was 1.2- 1.5mm. There were several or dozen guttules in the yolk sac, and only one was even bigger among them. At the temperature of 24 - 25 ℃, the fertilized eggs hatched to fries in about 69 hours and 23 minutes. These results would provide the imtportant scientific basis for the large-scale artificial reproduction and protection resources of the fish. And the optimal season of artificial reproduction is from May to June.