The utility model provides an adjustable reamer assembling workbench which mainly includes a base, a fixing bracket, a clamping slip, an adjusting screw, a lifting rod, a rotary bracket, a screw pressure plate, and the like, wherein the lifting rod is inserted to a fixing bracket barrel, and is fixed and connected with the fixing bracket through a pin shaft; the adjusting screw is in threaded connection with the fixing bracket; the clamping slip is connected with the adjusting screw through a pin; the rotary bracket is inserted into a lifting rod barrel, and the rotation and fixation of the rotary bracket are realized through a sliding groove and a pin; the screw pressure plate is in threaded connection with the rotary bracket; through rotating the screw, the screw pressure plate can downwards press a hydraulic power piston of a reamer to check the retraction and extension of blades of the reamer. According to the utility model, the outer diameter of the reamer capable of being clamped and fixed is adjusted through rotating the screw, and the screw pressure plate downwards presses the piston to check the retraction and extension of the blades of the reamer, so that safety hazards during assembly can be effectively eliminated, manpower is reduced, and the assembling efficiency of the reamer is improved.