Abstract: A racket stringing machine comprises a support frame, a tension head assembly, a lateral clamp head and a longitudinal clamp head. Movement of the tension head assembly is controlled by a brake motor which is controlled by the signals transferred from a limit switch. The limit switch is normally pressed by a contact element and released when a string clamp head pivoted on the tension head assembly is spring biassed to pivot away from the clamping frame and a contact element fixed on the string clamp head is separated from the limit switch. The lateral clamp head comprises two lateral clamp arms for clamping the lateral sides of a racket frame to be strung by a pivotal movement accomplished by an actuating block sliding along a rotating bolt. The longitudinal clamp head comprises a clamping sheet with a rack extending downward from the bottom surface for meshing with a sector gear so as to be rotated by a handle in order to clamp the upper surface of the racket frame.