The invention relates to a locating tensioning device of a corner clamping plate used for fixing an insulating tank in the curing stage after gluing. The locating tensioning device comprises an outerframe with inner side size larger than or equal to the side surface outline size of the insulating tank, and angle frames arranged at four corners of the outer frame, the angle frames comprises bottomplates fixed to the end angles of the outer frame, bases mounted on the bottom plates, guiding columns slidably penetrating through the bases, first connecting plates and second connecting plates correspondingly and fixedly mounted at the inner ends and the outer ends of the guiding columns, compression rollers arranged on the inner sides of the first connecting plates and used for being attachedagainst second concave right angle grooves, and compression springs sleeving the guiding columns, and the two ends of the compression springs abut against the first connecting plates and the base. Compared with the prior art, the assembling quality and the efficiency of the corner clamping plate can be improved through the locating tensioning device, mounting and disassembling operation are morerelaxed and can be operated by one person, in addition, the locating tensioning device can be piled up tidily in high density, full-automatic operation is convenient to achieved, and the logistic turnover efficiency is improved.