The invention discloses an entire bolt stretcher for nuclear reactor pressure vessels comprising a supporting ring, a lifting device, a supporting device, stretching component, a robot operating platform and a main bolt rotary robot. The supporting ring bears a reactor cover; the stretching component comprises a stretching hydraulic cylinder, a stretching bridge, a stretching nut, a stretching nut rotating device and a cover nut rotating device; the stretching cylinder is fixed to the supporting ring, the stretching bridge bears the piston of the stretching cylinder, the stretching unit is connected with a main bolt in a screwed manner, the stretching nut rotating device drives the stretching nut to rotate, the cover nut rotating device drives a cover nut to rotate, the lifting device drives the supporting ring to move upwardly, the supporting device supports the supporting ring, and the main bolt rotary robot is arranged on the robot operating platform and rotates the main bolt. The entire bolt stretcher is capable of screwing the main bolt in or out of a bolt hole in the pressure vessel and stretching the main bole so as to screwing the cover nut tightly or loosely, the operating efficiency is high, and disassembling time is saved.