The invention discloses a bentonite two-way swelling force measuring instrument, which comprises a fixation bolt, lock nuts, a top cover, a load sensor, stand column screw rods, a toss cap, a press head, an upper piston rod, a pipe connector, a seal ring, an expansion bucket, a water-permeable pad, a heat insulation pad, a heating ring, a strain foil, a temperature sensor, a bentonite sample, a temperature compensation sheet, a lower piston rod, a locating pin, a base, support legs and a data acquisition system. Swelling deformation data is obtained through the data acquisition system, and axial and radial swelling force are measured. The method is safe and simple to operate, and can measure the swelling force of the bentonite sample under a seepage condition or under a thermal environment and seepage dual conditions; and through the high-precision load sensor and the data acquisition system, test process is integrated, and parameters of the axial swelling force and the radial swelling force of the bentonite sample can be accurately monitored or calculated, thereby ensuring very high test precision and result reliability, and providing scientific and reasonable reference for scientific research and engineering application.