Clean energy, such as wind power and solar power, has been greatly developed in China, whose installed capacity has ranked the first in the world. However, the shortage of the matched storage facilities causes a lot of wind, solar and electricity abandonment. Pumped-hydro energy storage (PHS) plants currently dominate the energy storage market in China. Utilizing abandoned coal mine goafs as PHS reservoirs can not only enhance the efficient utilization of clean energy, but also reuse the wastes and protect the underground water resources. This paper investigates the preliminary feasibility of goafs as PHS underground reservoirs in terms of storable space and safe distance. The results show that as the permeability of goaf increases, the effective capacity of reservoirs rises. With the permeability above 8×10^-8 m², the effective coefficient(the ratio of effective capacity to total capacity) of underground goaf-reservoir can reach 0.8. A smaller horizontal distance between two reservoirs will lead to a larger leakage rate of the upper one and the acceptable distance for a typical coal mine geology is suggested.The results can provide a reference for the construction of coal mine PHES plants.