The invention discloses a method and a device for monitoring energy efficiency of heating furnaces. The method includes acquiring data of first index of the heating furnaces, calculating to obtain data of second index from the data of the first index by a counter-balance calculation method, and displaying energy efficiency index of the heating furnaces. The first index includes temperature and oxygen content of flue gas; the second index includes heat efficiency; and the energy efficiency index includes the second index. By the method and the device, status of the energy efficiency index of the heating furnaces can be monitored in real time.