The invention provides a tool for assembling a circuit breaker and a connecting lever box, and relates to the technical field of circuit breaker assembling auxiliary tools. The tool comprises a base used for being fixed relative to the connecting lever box, wherein the base is provided with a worm gear and worm pair, a shaft of the worm gear is provided with a rotation stopping connection structure which is in circumferential rotation stopping insertion with a main shaft of the main connecting lever, and the worm is provided with a screwing section. The base is fixed relative to the connectinglever box, the rotation stopping connection structure is enabled to be inserted and matched with the main shaft of the connecting lever box in place, and an operator manually screws the screwing section to drive the rotation stopping connection structure and the main shaft of the connecting lever box to rotate. The worm gear and worm transmission has a large transmission speed ratio, and the deceleration effect is more obvious. The angle of worm gear rotation is accurate when screwing is performed, thereby being convenient to control an insulating pull rod to move to the position at which theinsulating pull rod is articulated with an L-shaped connecting lever. In addition, the worm gear and worm pair has a self-locking function, thereby avoiding the position passing caused by the inertiaof the worm gear rotation, realizing the fast locking of the main shaft, and improving the operability in the actual assembly.