The invention discloses an overturning operation mechanism, comprises a chassis and a rolling cylinder which is rotatably arranged on the chassis, wherein a V-shaped notch is formed in the upper end of the rolling cylinder; two side walls of the V-shaped notch form object carrying table surfaces; the bottom end of the rolling cylinder is supported and connected to the chassis by two pairs of bearing rollers arranged on the chassis side by side; at least one winch is arranged on the chassis; two ends of a steel rope wound on each winch are fixedly connected to two ends of the bottom end of therolling cylinder; and the rolling cylinder can rotate around own axis on the bearing rollers under the drive of the winches so as to realize the overturning of the object carrying table surfaces. Theinvention also discloses a prefabricated pipe gallery overturning method. The overturning operation mechanism can realize the operation purpose of overturning dies, heavy objects, components and the like, and has the characteristics of simple structure, high operability, and low function realization cost and later maintenance expense.