The invention relates to a method for recovering an electrolyte of a battery and a recovery system thereof. The method for recovering the electrolyte of the battery comprises the following steps of: pulverizing the battery in a protective gas atmosphere to obtain a pulverized substance having a particle size of 0.2 mm to 5 mm; A subcritical fluid is use for subcritical extraction of that pulverized substance to obtain an extraction liquid, wherein the extraction temperature is between 20 DEG C and 40 DEG C, the extraction pressure is between 0.3 MPa and 0.8 MPa, and the subcritical fluid is n-butane in a subcritical state; And decompressing the extracting solution to obtain an electrolyte. The recovery method is environmentally friendly, has high recovery rate of electrolyte and high purity of recovered electrolyte.