Abstract: The quantitative assessment of water quality is beneficial to local governments in formulating and implementing water pollution prevention policies. The Huai River Basin (Henan section) is selected as the research area, aiming to study the spatiotemporal changes of water quality, and the impact of various land use patterns on water quality on the scale of administrative division of the Huai River Basin. According to the weekly data at 31 water quality monitoring sites from 2009 to 2017, the spatiotemporal changes of ρ(COD_Cr), ρ(NH₄⁺-N) and ρ(TP) concentrations and their correlation with land use patterns are analyzed with the assistance of remote sensing monitoring data of land use, the seasonal Mann-Kendall trend test and Spearman correlation analysis. The results show that:(1) During the study period, ρ(COD_Cr), ρ(NH₄⁺-N) and ρ(TP) show a significant downward trend in most regions. However, these water quality indexes still remain at a relatively high level. Specifically, ρ(COD_Cr) and ρ(TP) are slightly higher in wet season than in dry season, whilst ρ(NH₄⁺-N) is higher in dry season. (2) In terms of spatial characteristics, the rivers that have been severely polluted include:the Tuo River, the Hui River, the Huiji River, the Guo River, the Jialu River, the Qingyi River, the midstream section of the Ying River, the Heici River, the Fenquan River and the Hongru River. The water quality measured at most of these monitoring sites fell into Class Ⅵ or Ⅴ based on GB 3838-2002 Environmental Quality Standards of Surface Water, and the water quality at some sites even exceeded the GB 3838-2002 standards for Class Ⅴ category. In contrast, the water quality of the upstream of the Ying River, Beiru River, Sha River, the main stream of Huai River and Shiguan River are better and can meet the GB 3838-2002 standards for Class Ⅰ and Ⅱ. (3) The correlation between land use patterns and water quality demonstrates that ρ(COD_Cr), ρ(NH₄⁺-N) and ρ(TP) are positively correlated with the percentage of drylands and urban areas, but negatively correlated with the percentage of forest lands, grasslands, and unused lands. Additionally, the three indexes are negatively correlated with the proportion of water areas but the correlations were statistically insignificant. This research shows that the overall water quality of the Huai River Basin (Henan section) has been improved, but the water pollution problems in some parts of the area are still severe. The primary reasons resulting in water pollution, as the study indicates, are the drylands and urban lands, while forest lands, grasslands, unused lands and water bodies can alleviate water pollution.