A movable contact mechanism of a double-breakpoint circuit breaker comprises a front static contact having a first contact point at the rear end, a rear contact assembly having a connecting plate with a rear static contact at the front end, and a movable contact which are placed in the horizontal direction, wherein an insertion slot is formed in the front end of the rear static contact the front contact end of the movable static is equipped with a second contact point matched with the first contact point, and the rear insertion end of the movable contact is inserted into or separated from the insertion slot and the opening or closing stroke of the first contact point and the second contact point is greater than the stroke that the rear insertion end of the movable contact is inserted into or separated from the insertion slot.