A pressure control system for a torque control device includes a control pressure regulating valve (110) outputting a control pressure, a pressure switching valve (120) and a jointing pressure regulating valve (130) connected to a piston chamber of the torque control device. When the control pressure is lower than a set value of a spring of the pressure switching valve, the jointing pressure regulating valve (130) outputs jointing pressure that is in fixed proportion with the control pressure. When the control pressure reaches the set value of the spring of the pressure switching valve, the jointing pressure regulating valve (130) outputs a jointing pressure that is larger than the fixed proportion with the control pressure. The pressure control system ensures that the torque control device has both precise and large torque capacity.