The invention discloses a novel magnetic circuit gauge. The magnetic circuit gauge comprises a magnetic circuit gauge body, Magnetic steel and a magnetic bowl, wherein one end of the magnetic circuitgauge body is provided with an accommodating cavity for mounting magnetic steel; the diameter of the accommodating cavity is larger than that of the magnetic steel, a first ring conical surface is arranged on the magnetic circuit gauge body on the periphery of the accommodating cavity, correspondingly, a second ring conical surface is arranged in the magnetic bowl, the taper of the second ring conical surface is smaller than that of the first ring conical surface, and the second ring conical surface is connected with the first ring conical surface in an interference fit manner; The magnetic circuit gauge body at the bottom end of the first ring conical surface is provided with an annular clamping groove which is concavely arranged, correspondingly, the bottom end of the second ring conicalsurface is provided with an annular clamping block which is convexly arranged, and the annular clamping block is clamped in the annular clamping groove. The novel magnetic circuit gauge is compact instructure and convenient to install, the magnetic steel can be automatically clamped on the magnetic circuit gauge body through installation of the magnetic bowls, the problem that the magnetic circuit gauge body is damaged is effectively solved, and the service life of the magnetic circuit gauge is greatly prolonged.