The invention relates to an efficient dry air magnetic separator which comprises a frame. A hopper is fixedly connected on the upper part of the frame. A sealing shell is fixedly connected in the middle part of the frame. The sealing shell is connected with the hopper through a blanking pipe. A magnetic roller is arranged in the sealing shell, wherein the magnetic roller comprises a sleeve and a fan-shaped magnet arranged in the sleeve. The inner wall of the sealing shell and the part corresponding to the fan-shaped magnet form a flow guiding surface, wherein the flow guiding surface comprisesa plurality of wave segments, and the distance between the wave segments and the outer wall of the sleeve increases first and then decreases along the direction away from the blanking pipe. The sealing shell is also provided with a tailings discharge pipe, an iron refined powder discharge pipe and a dust removal pipe, wherein the iron refined powder discharge pipe is arranged far away from the fan-shaped magnet and the dust removal pipe is located above the iron refined powder discharge pipe. The frame is also provided with a driving mechanism for driving the sleeve to rotate. The wavy flow guide surface is arranged so that the ore sand particles far away from the outer side of the magnetic roller have the opportunity to contact with the outer surface of the magnetic roller or reach the vicinity of the surface of the magnetic roller, thus greatly improving the utilization rate of the magnetic field.