The invention discloses a column body connecting structure for a prefabricated building. The column body connecting structure comprises a base body assembly, a connecting block assembly and a column connecting assembly, wherein the base body assembly comprises a base rod, trapezoidal sliding grooves, a protruding insertion column, insertion holes, protruding bases, a bolt and a protruding insertion column insertion groove; the base rod is a square rod; the trapezoidal sliding grooves are arranged around the base rod; the protruding insertion column is fixedly connected to the center of the front end of the base rod; the plurality of insertion holes are uniformly distributed on the protruding insertion column; the upper end and the lower end of the rear end of the base rod are fixedly connected with the protruding bases; and the bolt is inserted and mounted between the two protruding bases.