Fisheries acoustics methods have been applied in fisheries investigation and research for decades, which superiored in direct, effectual, economical and does not result in fish mortality in fish sampling. They have been used to acquire the in situ information, such as fish abundances, temporal-spatial distribution and behaviours. Nanxi River is a model stream and is plentiful in fishery resources in the southern part of Zhejiang Province, which is located near the Wenzhou city. The Reach located in Shatou town, Fuli village Shizhu village and Lixi village (AreaⅠ—Ⅳ）is the major fisheries area. More than 37 fish species had acquired in those areas from 2007 to 2009, with Zacco platypus as the dominant species. In present study, the acoustical fish abundance assessment was conducted in the four Reaches of Nanxi River using EY60 split-beam echosounder (200kHz，Simrad) in 4th and 5th October, 2008. In post processing analysis, the GIS model had been applied to analysis the fish spatial distribution pattern in AreaⅠ—Ⅲ, using the interpolation method of inverse distance weighting (IDW). During such procedure, the survey areas were divided into numerous gridding cells by the grid size of about 30m×10m in the AreaⅠand AreaⅡ, and an grid size of about 10m×10m in the Area Ⅲ. The result showed that, the mean target strength of four investigation area is (-55.03±5.44)dB, and the standard length of fishes are ranging from 3 to 10 cm, with the mean length of 7cm, according to the empirical measures of target strength. The deviation of the fish sizes in the four area are not significant (P>0.05). The mean density of four survey area is 8.87 ind./1000m3, with the 95% confidence interval ranging from 1.66 ind./1000m3 to 16.09 ind./1000m3. The mean fish density of Area Ⅲ is (20.06±9.34) ind./1000m3, which is the highest fish density among these areas. The fish spatial distribution in each survey area are aggregated into plaque pattern, based on the GIS modeling. However, the fish distribution pattern of Area Ⅳ had not revealed in this study, for the zigzag transects of this area is not dense. As for the fish biomass, the four investigation area are all together possessed of 25 thousand fish individuals,the biomass of each survey area is 3971ind., 11478ind., 6587ind., 2978ind. respectively, according to vectoring grid technique of fish density, and the volume of element grid.