The invention relates to a main circuit current measuring device for a high-voltage DC transmission converter valve, which is arranged on a rectangular copper bar of a main circuit in a converter valve layer. The measuring device comprises a shielding case which is formed by butt joint of a shielding case I and a shielding case II, wherein the shielding case I is internally equipped with a magnetic core I winding a coil I, and the shielding case II is internally equipped with a magnetic core II winding a coil II, an integrating circuit and a voltage divider; an input terminal of the integrating circuit and the shielding case II are connected with the coil II, and an output terminal of the integrating circuit is connected with the voltage divider; and an output terminal of the voltage divider outputs a measuring signal. The current measuring device has the advantages of good shielding property, small volume, good linearity, high reliability, good stability, small influence for field intensity distribution in the converter valve and the like; and measuring range of the device is +/-10kA, frequency band is 40Hz-6MHz, sensitivity is 150mV/kA and maximum error is 1.22%.