The present invention relates to the technical field of high-specific-energy secondary batteries that can be charged and discharged. Disclosed is an ether-ester composite electrolyte solution for stabilizing a lithium metal battery. The ether-ester composite electrolyte solution comprises an ether-ester mixed solvent, an electrolyte, and lithium nitrate, wherein the molar concentration of the electrolyte is 0.5-4 mol/L, and the mass fraction of the lithium nitrate is 0.01-10% of the ether-ester compound electrolyte solution. The ether-ester composite electrolyte solution is prepared by introducing lithium nitrate as an additive into the ether-ester mixed solvent containing the electrolyte. According to the present invention, a metal lithium negative electrode can be effectively protected, and in a lithium metal battery using lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, or lithium cobalt oxide as a positive electrode, the cycle life of the battery can be obviously improved, good high and low temperature performance is achieved, and the ether-ester composite electrolyte solution is an electrolyte solution having great research value and industrialization potential.