Construction method of fabricated building structure and connecting piece of fabricated building structure

The invention belongs to the technical field of energy-saving building engineering, and particularly relates to a construction method of an assembly type building structure and a connecting piece of the assembly type building structure. L-shaped plates, a movable plate, a first threaded hole and a first hidden cover are arranged, so that when square pipes of different sizes are coped with, the distance between the multiple L-shaped plates can be finely adjusted, and the assembly type building structure is more convenient to use. At the moment, a plurality of L-shaped plates on the outer side can be pulled, so that the L-shaped plates move towards the outer side, when the L-shaped plates move, movable plates slide in corresponding side grooves, after the L-shaped plates all move to proper positions, bolts are in threaded connection with the interiors of corresponding first threaded holes, and at the moment, the bolts are located in first hidden holes; and then the first hidden cover is in threaded connection w