Magnetic latching relay which have switch function in the electronic watt-hour meter plays an important role in the power filed. But trip under the condition of the large current can cause injury of the magnetic latching relay contactor. Contactor can’t be open normally after multiple injury,even cause fire. Combined with the actual situation and the operating principle of the energy meter, this paper presents a soft design means to achieve the zero current crossing tript and to protect the magnetic latching relay from iniury caused by large current. Through Comparative experiments , the zero crossing trip has the advantage in protecting magnetic latching relay way and reduces the damage to the lower level .