The invention discloses a treatment instrument with a function of manually adjusting a tilt angle of a pedal. The treatment instrument mainly consists of a supporting plate, the pedal, a screw rod, a screw, a round ball and a handle. By adjusting the length of the tail end, penetrating through a columnar nut, of the screw rod, an angle between the pedal and a back supporting plate of the supporting plate can be changed; and when the lower limb of a patient suffers from spasm, the angle can be adjusted to be accepted by the patient, so that the sole props against the pedal, the knee is kept straight, the patient is assisted in stretching the lower limb, the pain of sole muscles is relieved, and the dependence on medical personnel is reduced.