An elevator braking device and an elevator system are provided by the present disclosure. The elevator braking device includes: a fixed frame; a floating bracket, which is disposed on the axial guide of the fixed frame and movable along the axial guide; a movable plate supported by the floating bracket, the movable plate having a second friction plate on a second side of the brake disc; an actuator; and a position self-adjusting member which includes a magnetic portion to act on the magnetic member on the floating bracket such that after the braking state is released, the floating bracket tends to move towards a balanced position, thereby reducing a difference between a first gap G1 between the first friction plate and the brake disc and a second gap G2 between the second friction plate and the brake disc.