The utility model provides a modular metering mutual inductor case, its characteristics are including the box, establish the bottom draw -in groove all around in the interior bottom of box, establish vertical draw -in groove respectively on the wall of the inboard both ends of front bezel of box, establish the layering of being connected with the transformer in the bottom of box, establish two insulating cement planks on two vertical draw -in grooves, offer four semicircle line holes on the two insulating cement planks respectively. The utility model discloses mutual -inductor case that will be original is by the fixed combination formula that changes into, has improved the installation effectiveness of mutual -inductor case, and safe operating performance is strong, easily uses widely.