The source region of the Yellow River (SRYR) is continuously affected by climate change and human activities, and water security problems have long existed and are constantly changing, with the possibility of inducing a series of new risks. To diagnose the above problems and clarify their evolution features, based on the connotation of water security and its involved dimensions, this paper systematically reviews the relevant research results on water security in the SRYR, summarizes the water security problems and their evolution trend in the region from three aspects: water disasters, water ecology, and water supply security, and deeply analyzes the cascade effect of each water security problem. This paper provides a scientific basis for carrying out water disaster prevention and ecological restoration in the SRYR, which is conducive to optimizing the development and utilization of water resources in the context of adapting to climate change.