Based on the combination of three evaluation methods, namely, the single constituent comprehensive evaluation method, the comprehensive contamination index method and comprehensive trophic status index method, the water quality monitoring data of centralized surface and ground potable water resources were comprehensively evaluated in plain terrain of Wuwei City in 2013. The results showed that ground water quality in the 4 monitoring sections were good; Surface water quality in the 4 monitoring sections of Xiying Reservoir, Huangyang Reservoir, Nanying Reservoir and Zhazigou during 4 quarters were fairly acceptable; The water quality in Redcliffe Mountain Reservoir was moderate; The water quality during the first three quarters in Xiaodongqiao were seriously contaminated, while in the last quarter in the region water quality was in moderate pollution. The comprehensive trophic statuses of the 4 monitoring sections of Nanying Reservoir, Redcliffe Mountain Reservoir, Xiying Reservoir and Huangyang Reservoir in 4 quarters were all poor. According to the evaluations, pollution prevention and control countermeasures of drinking water resources in plain terrain were proposed, which provides basis for drinking water protection and related research work in Shiyang River basin.