Water quality evaluation and driving forces analysis, two key factors to achieve ecological protection, resource utilization, and pollution control of water, are pivotal to the sustainable development of aquatic ecosystem. We utilized the in-situ experiment data of seven water quality parameters-dissolved oxygen (DO), transparency (Secchi disk depth, SDD), suspended particulate matters (SPM), chlorophyll a (Chla), ammonia nitrogen (NH₃N), total nitrogen (TN), and total phosphorus (TP)-which were collected from seven major basins in Guangdong Province during 2019-2020. This paper evaluates the water quality status of Guangdong Province in the high-flow season (HFS, N=66) and low-flow season (LFS, N=54) using the single factor index method (SI) and the comprehensive water quality index (WQI). The correlation between water quality parameters and driving factors, such as topography, meteorology, socio-economic and land cover types, were analyzed using Pearson correlation coefficient. The SI-based evaluation results show that the seven basins in Guangdong province are mainly faced with problems such as exceeding standard of Chla and TN concentration, and low DO concentration, which were caused by industrial sewage and agricultural non-point sources. The WQI evaluation results show that 57% of the sampling points in the study area are below the moderate level. The concentrations of Chla, SPM, NH₃N and TP have significant differences in water period and driving factors:the concentrations of Chla and TP in HFS are lower than that in LFS, but the concentrations of SPM and NH₃N are opposite in the two periods. The number of significant factors affecting the evaluation results of DO, TN, and WQI in LFS is about 1/3 of those in HFS. The seasonal difference is caused by the changes of complicated surface runoff and non-point source pollution, such as precipitation, nutrient load and land cover types in the basins. Water quality problems are prominent in the river network area of the Pearl River Delta, the lower reaches of the Hanjiang River, the rivers in western Guangdong, and the Lianjiang Basin of the eastern Guangdong. The water quality problems in the Pearl River Delta and the West River are mainly exceeded concentrations of TN and SPM. The main water quality problem of North River and East River is high TN concentration. The rivers in western Guangdong have insufficient DO, low SDD, and high concentrations of Chla and NH₃N. The conditions of TN and DO for some sampling points in the rivers of eastern Guangdong and the Hanjiang River are not optimistic. In the future, the integrated methods combining remote sensing monitoring, numerical simulation, and regular water quality evaluation models should be enhanced to explore the effects of non-point source pollution from climate change, riparian industrial structure, and adjustment of watershed land cover patterns. These integrated methods can help to further clarify the water quality impact of changes in rainfall intensity, production structure, and land cover patterns, which greatly promote the sustainable development of aquatic ecosystems.