Abstract: By using Biosonics DT-X echosounder (208 kHz), a hydroacoustic investigation was conducted on the fish resources in three mesotrophic reservoirs (Daxi Reservoir, Shahe Reservoir, and Jinniushan Reservoir) with different fishery management in late autumn and early winter 2011, and a GIS model was constructed to assess the fish resource distribution in the reservoirs. No significant difference was observed in the average size of fish in the three reservoirs, but the distribution curves of fish target strength (TS) showed that the fish size distribution proportion was different, and had close correlation with fishery management. The fish density in Daxi Reservoir (averagely 0.0183 ind·m^-3) had no significant difference with that in Shahe Reservoir (averagely 0.0124 ind·m^-3),but the fish density in Jinniushan Reservoir (averagely 0.0085 ind·m^-3) was significantly lower than that in Daxi and Shahe reservoirs. There was no significant correlation  between the horizontal distribution of fish density and the water depth in the three reservoirs. The fish in the three reservoirs were in group distribution, and fish aggregation was found in Daxi and Shahe reservoirs. In the three reservoirs, the fish biomass was the highest in downstream, and there was a greater biomass near the dam, except in Shahe Reservoir which was affected by fish catch activity. Based on the raster data obtained from GIS fish distribution model and the surface water area of each grid, the total amount of fish resources with the TS >-60 dB in the Daxi, Shahe and Jinniushan reservoirs was estimated as about 480000, 610000 and 520000 individuals, and that with the TS >-40 dB was about 50400, 52900 and 90700 individuals, respectively.