We collected the 35 literatures about water-demand for eco-environment of Lake Baiyangdian and systematically reviewed the methodologies and the corresponding calculation results. We identified the existing problem, and proposed research directions in the future according to the planning of the Xiong'an New Area. The statistical results shows that the lowest, suitable and highest water levels of Lake Baiyangdian are 7.45±0.66 m, 8.61±0.52 m and 9.46±0.51 m, respectively. Among the above three grades, water levels are highest in August and September, while lowest in May. In addition, extra water with the range of (1.35-6.20)×10⁸ m³ should be supplied to the Lake Baiyangdian annually to maintain the ecosystem status. However, the existing research on environmental water in Lake Baiyangdian is insufficient to support the construction of the New Area, such as significant differences in water-demand for eco-environment from various methods, the mechanism deficiency and rough time scales (year and month) in the ecological water demand calculation, without consideration the spatial heterogeneity in the lake and the connection of the lake and upstream rivers. Therefore, we proposed three research expectations, including the gridding and fine calculation, water quantity and quality simulation by restoring stages, as well as the recovering of the lake hydrodynamic process.