The study was carried out to assess surface water quality in Duyen Hai district, Tra Vinh province at 7 monitoring locations from NM1 to NM7 with the parameters studied inclue including pH, total suspended solids (TSS), dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), ammonium (N-NH4+), nitrate (N-NO3–), phosphate (P-PO43-), iron (Fe) and coliform to assess surface water quality in the years2020 and 2021. Surface water quality is assessed through comparison with the national technical regulation on surface water quality column A1 (QCVN 08-MT:2015/BTNMT). The study has applied statistical methods including cluster analysis and principal component analysis to group monitoring locations with similarity in the concentrations of parameters and determine the influencing parameters on surface water quality. The study results showed that the water quality in the study area appeared polluted in both years. Compared with column A1, all water quality parameters exceeded the allowable limits of QCVN 08-MT:2015/BTNMT (except pH parameter).Cluster analysis (CA) analysis has grouped from 7 monitoring sites into 3 monitoring groups, reducing 54% of monitoring costs for future monitoring programs. The results of the principal component analysis (PCA) analysis in the years 2020 and 2021 showed that there were 81.3% and 93.3% of surface water quality changes explained by three PCs and four PCs, respectively. All parameters used in the study should be further monitored in the upcoming monitoring program. Causes of pollution in the study area could originate from natural factors, acid sulfate soil, decomposition of plant residues in water, waste from agricultural and livestock production, farming, aquaculture and saltwater intrusion.