To study the spatial and temporal distribution characteristics of fish from Nan’an to Changshou River Section of the National Aquatic Germplasm Resources Conservation Area of the four major Chinese carps in the Chongqing Section of the Yangtze River (hereinafter referred to as the Chongqing Section of the Yangtze River Four Major Fish Reserve), and to provide basic data and scientific basis for the management and protection of fishery resources in this river section. Hydroacoustic detections were conducted in April 2018 (spring) and January 2019 (winter) in the study river section using a Simrad EY60 echo sounder. The results of the study showed that the spatial distribution of fish in the study river section was uneven, with fish mainly distributed in the upper layer of the water of the main branch-type section and the backwater tuyere-type section of the river in spring, and in the bottom and upper layer of the water around the dam in the middle of the river in winter; moreover, the density of fish in the section of the river in Guanyintan, where a tributary, Taohua creek, was also larger in spring and winter, with the densities of 365×10-2 and 810×10-2 ind·m-3, respectively, and the target intensity of fish in the study section ranged from -60 to 39 dB, the corresponding fish length ranged from 394 to 4955 cm, and the average length of fish was slightly larger in winter than in spring. Combined with the fish species diversity survey data and habitat analysis, the spatial and temporal distribution characteristics of fish in the study river section are closely related to the species characteristics, reproductive characteristics and habitat of fish in the upper reaches of the Yangtze River.