Analysis of uniformity for hydrological data is an important part of three characteristics (reliability, uniformity, representativeness) in hydrological analysis and water resources survey and assessment. For the need of both water resources monitoring and flood control, replacing siphon rainfall recorder with telemetering tipping-bucket rainfall recorder can shorten the travel time of precipitation information, increase fore - cast lead time of flood forecasting and establish foundation of modernization for water resources monitoring. The uniformity of observational data are impacted because of the different resolution between telemetering tipping -bucket rainfall recorder and siphon rainfall recorder. The error range was quantitatively analyzed by comparing the various observation precisions of different durations.