Three-phase asynchronous motor test prototypes with IE5 energy efficiency grade have been designed and developed by using cast copper rotor technology, low-voltage unequal turn winding technology, low loss silicon steel material and other technologies. In order to accurately measure the field operation efficiency of three-phase asynchronous motors, the energy efficiency comparison test of the developed prototypes is carried out by using methods A, B and E1 according to the national standard GB/T 1032—2012 Test procedures for three-phase induction motors, and the differences among the three test methods are studied and analyzed. For the three series of IE5 energy efficiency grade prototypes tested, the calculation efficiency of method B can meet the requirements of grade-1 energy efficiency in GB 18613—2020 Minimum allowable values of energy efficiency and values of efficiency grades for motors.