In this study, virtual confluence of 30°, 45°, 60°, 75° type flowing into main channel was designed to comprehendocclusion phenomenon of the mouth of river, then performed numerical analysis using the RMA-2 and SED2D model ofSMS according to application of 40m, 60m, 80m, 100m Training levee corresponding to main channel width ratio. Resultsof simulations analysis are summarized as follows. Applying appropriate Training levee length determined by numericalanalysis results, Training levee dimension for occlusion reduction was studied through the analysis of velocity, water level,bed variation at the Gamchen confluence and Wichen confluence.