The invention discloses a shaping method for an Archimedes curved surface wedge block of a sprag clutch. The shaping method comprises the steps that a shaping characteristic curve is determined according to an Archimedes curve of a lower cam of the wedge block; a shaping coefficient is determined according to the ultimate torque and the ultimate wedge block inner wedge angle; and a mechanical model of a shaping clutch is determined according to the Hertz theory and the thick-walled cylinder theory. According to the step that the shaping characteristic curve is determined according to the Archimedes curve of the lower cam of the wedge block, the shaping characteristic curve equation is rho=rho0+a theta+mu theta <2>, wherein rho0 is the initial polar radius, theta is the polar angle, a is a coefficient, and mu is the shaping coefficient. By the adoption of the design method, the good impact resistance of the Archimedes curve is maintained, the wedge block inner wedge angle V of the sprag clutch is made to increase gradually in the wedging process, and the bearing capacity of the sprag clutch is improved.