The invention provides a flow coefficient 0.0618 light-medium high-energy-head compressor model stage and a design method thereof. The model stage comprises an impeller, a blade diffuser, a curve anda reflux device, the blade diffuser is arranged at an outlet of the impeller which is positioned at an inlet position of the model stage, the reflux device is positioned at an outlet position of the model stage, and the blade diffuser is communicated with the reflux device through the curve. In the model stage, a machine mach number Ma2 is 0.2-0.65, a design point flow coefficient phi 1 is 0.0618,a design point energy head coefficient tau is 0.69, a polytropic efficiency eta pcl under a designed flow coefficient operating condition is 0.889, and an applied flow range is 0.65-1.67 of a designpoint. The model stage is high in efficiency, high in energy head coefficient, large in hub ratio and small in span; by adoption of the model stage, high operating efficiency and a wide operating condition range of a light-medium compressor can be realized, reduction of rotor rotating speed in operation is benefited, and bearing span shortening and rotor stability improvement are realized.