In order to discuss the variation characteristics and the sources of water pollution in Baiyangdian Lake, ions, nutrients (nitrogen and phosphorus) and heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in the waters were studied to analyze the spatial and temporal variations, as well as to discover the influencing factors and main sources using multivariate statistical methods. The results show that the hydrochemistry types included HCO3-Ca·Mg and SO4·Cl-Ca·Mg, and the average values of TN and heavy metals in Baiyangdian Lake exceeded the water quality limits of class V. The average values of TN and TP in the past 20 years displayed a trend of decreasing volatility and had no obvious correlation between each other, which were mainly affected by climate and human activities. Spatially, the nutrients and heavy metals in the waters of Baiyangdian Lake were relatively high in the west and low in the southeast. Multivariate statistical analysis further confirmed that the pollutants carried by Fuhe River are the main source of nutrients and heavy metals in waters of Baiyangdian Lake, which are also the main factors affecting their spatial variations. However, the influence of human activities on elements in different regions within the lake area cannot be ignored, especially N, P, Pb and Cr.