There exist several ideas upon the cause of formation of Baiyangdian Lake. North China Plain. Recently, Zhu Xuanqing, et nl (1994) pointed out that Baiyangdian Lake used to be an outcome of human activities in the book titled “Environmental Evolution and Prediction of Baiyangdian Lake” (Xi'an Atlas Press, 1994. ). That conclusion drawn by Zhu,et al (1994) was based on the follows: 1) The geographical environment during the Middle Holocene in the plain was not suitable for lake formation ； 2) The existence of Ltitnprotula spp. fossils in the sediment revealed a corresponding fluvial sedimentary condition; 3) The historical remains of Neolithic Age and Zhangguo Dynasty demonstrated that there was not a vast and unified lake at that time. The authors here present a new look on the above views. It was the differential accumulations of various rivers that formed Baiyangding Lake,a lake between alluvial fans and rivers. The lake has its own emergence, development as well as dry-up processes during its evolution history. Human activities could trigger the outcome of expansion,reduction and even dry-up in history. whereas each was merely one of the different stages in the evolution history of Baiyangdian Lake, instead of the cause of formation instead.