An improved mechanism of electric lock for door, comprising a case, on both side of the opening of the case arranged keeper arms, drive rods, and rotate member, and a drive mechanism connected to a drive member and a brake member; to achieve lock mode, the drive member drive the brake member to be engaged with the rotate member, making the keeper arms and drive rod unable to rotate, so the keeper arms can block the latch bolt from going through the opening; to achieve unlock mode, the drive member drive the brake member to be separate from the rotate member, making the keeper arms and drive rod able to rotate, so the latch bolt is able to go through the opening.