Beijiang River, the second largest river of the Pearl River Basin, is an important species gene pool which has 143 species fish in datum. Shijiao reservoir is the first cascade river-type reservoir between Qingyuan hydro-junction and Feilaixia hydro-junction. Because of the blocking effect and other human activities, fishery resources had a declined tendency. Up to now, no relative research was reported in this area since the hydro-junction was built, so the actualities of fishery resource is unknown. To understand the current situation of fish resource, a split beam echosounder EY60 (120 kHz, 200 W) was used to survey the fish resource and behavior feature from 2015 to 2016 in different seasons. All the surveys were divided into a certain elementary distance sampling unit EDSU, so that for every survey, 200-250 EDSU with independent estimates of biomass, density and behavior were available. Echoview 4.9 was used to process acoustic data. The results show that there was significant difference in fish density, behavior feature in different survey periods and different survey areas. The average fish density in the survey area was (0.008±0.0125) ind/m³ in December 2015, (0.1601±0.1123) ind/m³ in March 2016 and (0.0405±0.0449) ind/m³ in June 2016 respectively. Fish individuals had evident seasonal variation tendency, characterized that fish mainly resided in dam area in winter and spring and migrated to upstream area in summer. According to the vertical distribution data, fish mainly distributed in 4-12 m layers and the distribution had significantly difference in different area (<0.01). Fish's behaviors such as swimming speed, swimming direction and depth preference were significantly different in different season. Take migration direction as examples, fish mainly migrated horizontally from dam area to upstream area and swimming down in vertical direction in summer, winter has opposite situation. As a whole, this study reveals a clear pattern of fish distribution, migration and behavior feature in different season, and shows the applicability of acoustic method to study fish behaviors in large scale area. The results can provide reference for fishery resources sustainable development and fishery engineering design of Beijiang River.