The invention provides an automatic lifting device of a heavy-load roof door. The device is provided with four main body mechanisms, wherein the four same main body mechanisms are fixedly arranged on four corners of a wind tunnel roof door respectively; a roof rood support arm is arranged at the upper end of a movable guide rail by a horizontal-sliding roller; the lower end of the movable guide rail is connected with the upper end of a jacking spiral lifter by a self-adjustment flexible mechanism; two sides of the movable guide rail are connected with a guide plate by a guide roller; the guide plate is connected with a base and a fixed guide rail; a left side and a right side at the lower end of the movable guide rail are provided with an adjustable positioning support pillar respectively; and a pulling tray moving motor is connected with a pulling tray. Each industrial control computer is provided with an operation interface and a motion control program, and by a motion control card and an IO expansion card of the computer, motion control of an alternating current servo motor can be realized by using a motion control function of the control card. By the device, the heavy-load roof door can be automatically opened and closed, and the device is stable, reliable and safe to operate.