This paper has a discussion on the method of improving the precision of tidal discharge based on analyzing the data of tour gauging tidal discharge in Pearl River Delta. The precision of determination of relation curve of representative vertical velocity can be improved by using the method with multi-factor such as representative vertical velocity, tidal level and rate of rise and fall of tidal level as correlation, which can not only decrease the labor intensity and cost of tidal discharge measurement, but also improve the quality of tidal discharge measurement and data processing, so as to increase economic benefits.