Water quality is critical for a healthy ecosystem, this study was conducted to evaluate the surface water quality in lakes in An Giang Province from 2017 to 2019. Water quality was assessed using variables of temperature, pH, dissolved oxygen (DO), total suspended solids (TSS), chemical oxygen demand (COD), biological oxygen demand (BOD), nitrate (NO₃^--N), phosphate (PO₄^3--P), ammonia (NH₄⁺-N), and coliforms at nine locations  belonging to seven reservoirs including O Tuk Sa, Thuy Liem, Soai So, Soai Chek, O Thum, O Ta Soc, and Bung Binh Thien. Water quality criteria were assessed according to the National Technical Regulation on Surface Water Quality (QCVN 08-MT: 2015/BTNMT). Cluster analysis (CA) and principal component analysis (PCA) were applied to group water quality to identify the main parameters affecting water quality in the reservoirs. The findings indicated that the water quality in the reservoirs were polluted by TSS, organic matters (DO was low, while COD and BOD were high), and microorganisms (coliforms). The PCA analysis showed that the water variables including temperature, pH, DO, TSS, COD, BOD, NO₃^--N, PO₄^3--P, NO₃^--N, and coliforms significantly influenced the surface of the water in the reservoirs. It is necessary to investigate pollution sources to propose appropriate solutions to treat and maintain the water quality in the reservoirs of An Giang Province .