The invention discloses a semi-active suspension based on magnetically controlled shape memory alloy, which comprises an upper connecting ring, a lower connecting ring, a sensor, a controller and a damper shell, wherein an upper iron core and a lower iron core are fixed on the damper shell, first and second magnetically controlled shape memory alloy bars are respectively filled on the upper iron core and the lower iron core, and excitation coils are respectively wound on the upper iron core and the lower iron core; one end of an upper tappet of the damper is connected with the upper connecting ring, the other end of the upper tappet is in contact with the first magnetically controlled shape memory alloy bar, and the other end of the first magnetically controlled shape memory alloy bar is connected with an upper push rod; and one end of a lower tappet of the damper is connected with the lower connecting ring, the other end of the lower tappet is in contact with the second magnetically controlled shape memory alloy bar, and the other end of the second magnetically controlled shape memory alloy bar is connected with a lower push rod. The semi-active suspension disclosed by the invention can improve the smoothness and comfort of a vehicle, damp vibration, adjust the vehicle body height and turning posture, as well as eliminate the hidden danger of leakage of hydraulic oil of a traditional double-drum hydraulic damper.