The invention relates to a circuit breaker capable of adjusting instantaneous tripping current. The circuit breaker comprises a shell and a clapping type tripping device, wherein the clapping type tripping device comprises a tripping mechanism, an excitation conductor, a magnet yoke and an armature; the magnet yoke comprises two side plates arranged in opposite and a spacing cavity formed between the two side plates; the armature is mounted in the shell through a rotation shaft; the lower part of the armature extends along the length direction of the rotation shaft to form a clapping surface that is wider than the distance of the two side plates; the clapping surface and the end planes of the two side plates are matched in a clapping manner; a reset elastic element is arranged on the exterior of the rotation shaft in a sleeving manner; the magnet yoke is provided with a magnetic conducive rod along the spaced direction of the two side plates, and the magnetic conducive rod can move along the axial direction; one axial end of the magnetic conducive rod passes through one side plate to extend into the spacing cavity of the magnet yoke while the other axial end of the magnetic conducive rod extends out of the spacing cavity; and an insulating adjusting rod is arranged on the magnetic conducive rod and used for driving the magnetic conducive rod to axially move so as to adjust the depth of one end, extending to the spacing cavity, of the magnetic conducive rod. The circuit breaker has the advantages of simple structure, easy machining and realization, convenient adjustment operation, and easier control of adjustment precision.