The utility model provides a multistage heat -retaining device, cryogenic liquefying air energy storage system who uses multistage heat -retaining technique and defeated thermal system of power storage, the heat -retaining device includes: two at least heat reservoirs are adjacent establish ties with the help of the defeated passage of heat between the heat reservoir, at least one the output of heat reservoir and heat energy is connected, at the heat -retaining in -process, preceding one -level heat energy that heat reservoir heat -retaining in -process spills over with the help of the defeated passage of heat gets into the back one -level in the heat reservoir, for the back one -level the heat reservoir preheats, and the tail gas of release still contains certain heat energy in the preceding one -level heat reservoir, preheats the back to back one -level heat reservoir again, and the heat storage medium in the heat reservoir is given in the exchange that heat energy in the tail gas can great limit to the storage rate of the improvement heat energy of great degree avoids heat energy extravagant.