A circuit breaker for motor protection includes a contact support installed in a housing, a static contact assembly and a movable contact assembly mounted on the contact support, and also includes a rotary handle and a linkage mechanism connected with the rotary handle. The linkage mechanism comprises a gear swing rod and a push rod. The rotary handle rotatably drives the linkage mechanism to drive the push rod to make the movable contact group on the contact support come into contact with and separate from the static contact group. One end of the rotary handle is provided with an upper gear intermeshed with the gear swing rod. The upper gear comprises teeth. A tooth groove is formed between every two adjacent teeth. The gear swing rod is provided with swing rod teeth corresponding to the tooth grooves. Swing rod tooth grooves corresponding to the teeth are formed between the swing rod teeth. The teeth gradually narrow from the inside to the outside. First inclined surfaces are formed on both sides, and second inclined surfaces corresponding to the first inclined surfaces are disposed on both sides of the swing rod tooth grooves.