Based on the water quality data of eleven monitoring sections in the lower reaches of Xijiang River Basin from 2005 to 2017 and remote sensing data in 2005, 2010 and 2018, the influence of land use structure at different spatial scales on the water quality in the lower reaches of Xijiang River Basin was analyzed by methods such as Spearman rank correlation coefficient method and redundancy analysis through different spatial scales and division of land-use types. The results show that from 2005 to 2017, the water quality of the main stream of Xijiang River, Hejiang and Luoding River was good in general, while water quality of Xinxing River and Nanshan River deteriorated significantly. Meanwhile, TP concentration in the main stream of Xijiang River in the flood season was obviously higher than that in the non-flood season. At the scale of river basin, the river water quality index was significantly positively correlated with construction land while significantly negatively correlated with water body. At the scale of river bank buffer zone, the river water quality index was negatively correlated with forest and water body. The interpretation of construction land to COD was relatively high, and the interpretation of construction land in 800 m buffer zone to TP and NH₃-N was the highest. The correlation of river water quality index and dry land rose significantly when buffer zone reached 1 500 m, and the impact of paddy field in 800 m buffer zone on river water quality index was great. It is suggested to strengthen pollution control measures for construction land, paddy field within 800 m and dry land outside 1 500 m buffer zone.