The invention discloses a quantitative assessment method for efficiency of a back heating type compressed air energy storage system. The method aims at the back heating type compressed air energy storage system, and an integral quantitative assessment is divided into a quantitative assessment of part segment efficiency and a quantitative assessment of integral segment efficiency, and the quantitative assessment of the part segment efficiency is the quantitative assessment for compressed energy storage segment efficiency, back heating segment efficiency, air storage and discharge segment efficiency and energy expanding and releasing segment efficiency; the quantitative assessment of the part segment efficiency serves as quantitative assessment value of the part segment efficiency according to change of the ratio of input value and output value of the part segment efficiency or energy; the quantitative assessment of the integral segment efficiency is obtained by calculation according to the energy expanding and releasing segment efficiency, the compressed energy storage segment efficiency and exchange value between the energy expanding and releasing segment efficiency and external technical function and between the compressed energy storage segment efficiency and the external technical function; according to the obtained assessment value of each part segment efficiency and the obtained system integral efficiency by calculation, the back heating segment efficiency of the back heating type compressed air energy storage system is confirmed.