Abstract: The Hanjiang River is a tributary of the Yangtze River, where the fish resources are rich. At present, there are four dams having been constructed in the middle and lower reaches of the Hanjiang River, which have greatly influenced on fish migration and reproduction. In order to promote fish propagation in the middle and lower reaches of Hanjiang River, the combined eco-operation of cascade reservoirs was firstly carried out in June 2018. In this study, we set up a monitoring station in Hanchuan, locating in the lower Hanjiang River, to capture the fish larvae and eggs. Our aims were to study the species diversity and abundance of fish early life resource and the effects of eco-operation on the fish reproduction in the lower Hanjiang River. The results revealed that thirty-six fish species or genus were identified from the captured larvae and eggs, twenty-two of which produced drifting egg. The total quantity of fish larvae and egg was 11.878 billion, with 11.378 billion of larvae and 0.55 billion of egg. The total quantity of four domestic Chinese carps’ larvae and egg were estimated to be 87 million and accounted for 0.73 percent of total larvae and egg. Four spawning grounds of four domestic Chinese carps in the lower river were deduced according to the development time of fish egg and water velocity. During the combined ecol-operation of cascade reservoirs of the Hanjiang River, a spawning peak was found in the lower reaches and the egg abundance of the peak accounted for 34.1 percent. A spawning peak of the four Chinese farmed carps was also detected in this period and the egg abundance accounted for 85.5 percent of all captured these fishes’ egg. It indicated that eco-operation of cascade reservoirs had a positive effect on fish reproduction activities in the lower Hanjiang River, especially for the four domestic Chinese carps. We suggested that ecol-operation should be continuely scheduled and the monitoring works and data analysis should be focused in the future.