Abstract: The measurement of velocity of shallow water flow is of great importance for hill-slope hydrology and soil erosion prediction. The electrolyte tracer pulse model was found to be unable to predict the velocity correctly at short distance though it is desired for portable apparatus development. In this paper, electrolyte tracer normal distribution model was proposed by using Normal distribution function as boundary condition instead of pulse function to predict velocity of shallow water flow. An improved method for measuring the flow velocity was advanced based on the Normal Distribution Model, which uses the convolution integral of the pulse response and the normal distribution boundary as the more realistic solution to the solute transport processes. By fitting the Normal Distribution Model with the actually measured solute transport processes, the flow velocity values under different conditions were estimated. Compared with the velocity values measured with the pulse model, the Normal Distribution Model reduced the measurement errors at different locations to different degrees. The results will provide theoretical foundation for advanced apparatus development of velocity measurement.