The embodiment of the invention provides an unlocking device of a coupler of a railway car and the railway car. The unlocking device comprises a lever frame arranged on a first uncoupling lever bracket, a first uncoupling lever, a second uncoupling lever and a lock lifter for opening the coupler. An upside transverse lever of the lever frame is fixedly arranged in the first uncoupling lever bracket and acts as the axis of rotation of the lever frame. The first uncoupling lever and the second uncoupling lever are respectively connected with left and right upright levers of the lever frame. The lock lifter is connected with a downside transverse lever of the lever frame. The embodiment of the invention also provides the coupler and the railway car. By arranging the unlocking devices at both sides of the coupler, the rear coupler of the front car unit and the front coupler of the rear car unit can be simultaneously opened at any side of the railway line during hump marshalling operation, thus improving the efficiency of car marshalling.