The invention provides a positive tool clamp of a radiator, and the positive tool clamp can solve the technical problems that use is relatively complex and clamping efficiency is low when an existing clamp is used for clamping the radiator. The positive tool clamp comprises a bottom plate. The positive tool is characterized in that clamping mechanisms are separately arranged on positions, which correspond to the left side and the right side, of the bottom plate; each clamping mechanism comprises an air cylinder, a pressure plate, a guide base and a fixed part; one end of each pressure plate is pressed on the radiator, and the other end of each pressure plate is in sliding connection with a slide sot in the guide base; a strip-shaped through slot is formed in each pressure plate; one end of each fixed part passes through the corresponding strip-shaped through slot for fixing the corresponding pressure plate to the end part of a piston rod of the corresponding air cylinder; each fixed plate can be detachably connected with the piston rod of the corresponding air cylinder; a front side positioning base, a rear side positioning base and left side positioning bases are correspondingly arranged on the positions, which correspond to the front side, the rear side and the left side of the radiator, of the bottom plate; the left side positioning bases comprise a left side front positioning base and a left side second positioning base which are oppositely arranged; and the front side positioning base and the left side front positioning base are separately in threaded connection with regulating bolts.