Abstract: In order to analyze the pollution sources and the spatial and temporal distribution of water quality in Cihu Lake, the principal component analysis (PCA) of pollution factors was conducted based on the water quality monitoring data of Cihu Lake from 2015 to 2019, and the contribution rate of pollution sources were calculated by absolute principal component score-multiple linear regression (APCS-MLR) receptor model, and the inverse distance weight interpolation (IDW) method was used to analyze the spatial and temporal distribution pattern of water quality. The results showed that the 1st, 2nd and 3rd principal components affecting the water quality of Cihu Lake were urban non-point sources, urban domestic pollution sources and meteorological factors, respectively; the contribution of the 1st principal component to BOD₅ (88%), COD_Cr (76%), COD_Mn (67%), NH₃-N (55%), TN (46%) and TP (67%) was the largest, and the contribution of the 2nd principal component to BOD₅ (39%), NH₃-N (32%) was larger. Overall, the main pollution sources of Cihu Lake were urban non-point sources and urban domestic pollution sources. From the spatial and temporal distribution map of the water quality, it could be seen that the most serious pollution was at the inlet of Xialu Port (point 1#), which was mainly affected by the siltation of bottom mud formed by the production of historically industrial and mining enterprises and urban domestic sewage in the upstream area.