Water level change is an important factor that influences the lake's environment, which is considered to be a dynamic reflection of its hydrological processes and water balance. Over the past 100 years, the water level in the Lake Baikal, the largest freshwater lake in the world, has exhibited a large annual, inter-annual, and multi-year variations under the dual stress of natural changes and human activities. The water level change of the Lake Baikal is highly associated with runoff variation into the lake, which is consistent with the runoff variation of the Selenga River, the largest tributary of the Lake Baikal. The increasing temperature and decreasing precipitation caused by climate warming reduced the inflow to the Lake Baikal, causing the decline in the lake's water level. The influence of human activities on the changes of water level in the Lake Baikal is manifested in two aspects. First, agricultural expansion under the global warming and associated increasing water consumption by irrigation has led to an increasing water consumption, reducing the surface water flow into the lake and declining the water level of the Lake Baikal. Second, water level change is affected by jacking of the Angara River after operating the Irkutsk Hydroelectric Power Station. Under the human control of the downstream hydropower station, the water level distribution asymmetry increases annually, the amplitude of water level fluctuation increases seasonally, and the date of annual minimum and the highest water level is delayed. The level change of the Lake Baikal, which is located in the sensitive region of global climate and environmental change, has a significant impact on the ecological environment of the lake and its surrounding area. Therefore, the research on the water level change in the Lake Baikal and its influencing factors has an important significance for protecting the local environment in the context of global change.