Disclosed is an energy storage system using supercritical air, comprising compressor units (1, 3), heat exchanger and storage device (2, 4), a throttle valve (5), a cryogenic tank (6), a cryogenic pump (8), expander units (9, 10), a generator (11), a driver unit (12), and a plurality of pipes. There are several advantages of this invention, including high energy density, high efficiency, no storage cycle and geographical conditions restriction, easy implementation with all kinds of power stations, environment friendliness and capability of recycling low to medium temperature waste heat and so on.