The invention belongs to automatic ultrasonic nondestructive detection devices of reactor pressure vessel top cap penetrating pieces and other pipe fittings in a nuclear power station, and particularly relates to an ultrasonic detection probe combined structure in a pipe fitting. The combined structure comprises a shell; a top cover plate is arranged at the top of the shell; a combined structure body is arranged in the shell; a bracket is arranged between the combined structure body and the top cover plate; a small camera is arranged at the middle of the bracket; a push plate is arranged in a cylindrical cavity at the upper part of the combined structure body; a set of ultrasonic probes are arranged on the push plate; a piston is arranged on a position on the combined structure body and corresponding to the middle of the push plate; and the middle of the piston is communicated with an air path. The combined structure has the advantages that four ultrasonic probe body installing structures are arranged on the combined structure body, and four probe bodies can be hidden in the combined structure body, and also can be exposed partially under the drive of an air cylinder structure. The combined structure can realize functions of flexible movement of the ultrasonic probes, stable coupling of ultrasonic waves, lighting shooting and the like.