This paper introduced the flow data check in the hydrological data processing. According to the flow measuring start and stop time for discharge computation, this paper found the water level in the concerned telemetered water level file, compared the water level data in the file with the observed water level data, put the different in a file, and then transfer discharge computation process and flow measuring process into DAT file, plotting to the process of water level line on CAD diagram so that to check the time data. At the same time, comparison was made between the water levels in the discharge computation file.