The invention relates to the technical field of insulating pipes, in particular to an assembling device of a prefabricated direct burial anticorrosion Insulating pipe. The assembling device comprisesa conveying mechanism and an adjusting mechanism. The conveying mechanism comprises an adjusting support, a base, a drive motor and a conveying belt. The conveying belt is arranged on the adjusting support. The bottom of the adjusting support is fixed to the base through bolts. The conveying belt is driven by the drive motor to rotate. The adjusting mechanism is arranged on one side of the conveying mechanism and comprises an adjusting support, an adjusting plate, an adjusting motor, a rubber roller, conveying shafts, a bearing pedestal, a rubber check block and a lifting air cylinder. The lifting air cylinder is fixed to the center position of the bottom of the adjusting support. A piston rod of the lifting air cylinder is connected with the bottom of the adjusting plate. The surface of the rubber roller is in contact with a to-be-conveyed steel pipe. One conveying shaft is connected with the output end of the adjusting motor. The device replaces traditional crown block equipment, andcost is saved.