The invention discloses an electricity theft prevention ammeter case device, comprising an ammeter case body which is connected to a case cover; the ammeter case is internally provided with a plurality of ammeters; the ammeter case is internally provide with electric energy meter cases, wherein the quantity of the electric energy meter cases is matched with the quantity of the ammeters and the electric energy meter cases can shield the magnetic field; the outer end surface of the back side wall of the electric energy meter case is connected to the inner wall of the ammeter case; the lower side wall of the electric energy meter is provided with a wire inlet-outlet hole for the ammeter connection wire; the shape and the size of the inlet-outlet hole is matched with the shape and the size of the cross section of the ammeter connection wire; the ammeter is installed inside the electric energy meter case; the electric energy meter case adopts a cuboid cavity structure or a cube cavity structure which is matched with the appearance of the ammeter; every adjacent planes of the cuboid structure or the cube structure are connected through an arc surface; and eight apex positions adopt curve surfaces which smoothly connect three curve surfaces. The cabinet is reliable in sealing and good in strong magnetic interference, which improves the reliability and accuracy of the electricity theft prevention device.