Abstract: Firstly, the Chinese and IEC standards for electric vehicle AC charging system are compared in terms of mapping relationship of physical interface, control pilot circuit, proximity detection circuit, pulse width modulation（PWM） duty cycle.Secondly, the technical differences between the two schemes are studied, and the cross-coupling results of the physical interface between the Chinese scheme and the IEC type2 scheme in Case B connection mode under the condition of the tolerance stack are calculated. And the possible interoperability problems are analyzed. Finally, the standard modification suggestions of the interoperability between the two schemes and the international standardization scheme of Chinese AC charging system are put forward.