The SSARR model adopting IS(integrated snowband) watershed model is applied to the Nakdong River basin for low flow analysis. The IS watershed model is added to new version of the SSARR which has functions of simulating evapotranspiration. infiltration and lower zone routing. It provides annual water budget information as an output file and can be operated by interactive mode. Sensitivity analysis for both cases of high and low flows was carried out, which becomes the knowledge base for model calibration. Model verification was performed using the relative errors of high flows and absolute errors of low flows at the control points. Monthly water budget analysis was done by IS watershed model. and it reveals that runoff coefficient is 52.6% Keywords: low flow analysis, SSARR-8 model, IS watershed model. water budget analysis