The invention discloses a commercial semi-trailer closed-loop electric control brake hysteresis compensation device which aims at solving the problem that during automobile and train braking, trailer brake hysteresis is caused and the trailer brake strength cannot be controlled. The device comprises a tractor mechanical part, a trailer mechanical part and a controller (11). The tractor mechanical part comprises a first pressure sensor (3). The trailer mechanical part comprises a first electromagnetic valve (4), a second pressure sensor (6) and a second electromagnetic valve (7). The controller (11) comprises an A/D conversion chip (24), a first relay (30) and a second relay (31). The third port of the first pressure sensor (3) is connected with the twenty-sixth port of the A/D conversion chip (24), the third port of the second pressure sensor (6) is connected with the twenty-seventh port of the A/D conversion chip (24), the first electromagnetic valve (4) is connected with the fifth port of the first relay (30), and the second electromagnetic valve (7) is connected with the fifth port of the second relay (31).