The invention discloses a combined wind-driven grain cleaning machine and a combined wind-driven grain cleaning method thereof. The combined wind-driven grain cleaning machine comprises a cyclone separator, an inclined pipe grain cleaning machine body, a dust collector and two high-pressure fans. Multiple slope microstructures of the inclined pipe grain cleaning machine body are arranged into a parallel multi-column structure including a first-stage inclined pipe, a second-stage inclined pipe and so on. A material outlet of the cyclone separator is located at an inlet of the first-stage inclined pipe. An included angle of 45-70 degrees is formed between an upper inclined pipe and a lower inclined pipe of each slope microstructure and the horizontal plane, and the upper inclined pipe and the lower inclined pipe of each slope microstructure incline in the opposite directions. A plurality of guide strips are arranged on the inner surface of each inclined pipe in a staggered mode, the heights of the guide strips are in the range of one third to half of the radial width of the corresponding inclined pipe, and the angles between the guide strips and the horizontal line is kept to be 45-80 degrees. The first high-pressure fan communicates with an impurity outlet of the cyclone separator to generate negative pressure, and the second high-pressure fan communicates with the lower inclined pipes of the inclined pipe grain cleaning machine body to generate positive pressure. The dust collector is arranged on the tops of the upper inclined pipes and communicates with the first high-pressure fan.