The invention discloses a portable combined grain harvester which comprises a stand. A threshing device, a winnowing device and a cleaning system are arranged on the stand front and back in sequence; a threshing roller and a grain conveying auger are assembled in the shell of the threshing chamber of the threshing device in a way of rotating up and down; the axis and the feeding port of the threshing roller both extends front and back; a feeding device comprises an upper cylindrical auger rotationally assembled on the feeding port; a lower cylindrical auger is rotationally and juxtaposedly assembled outwards below the upper cylindrical auger; the internal common tangents of the upper cylindrical auger and the lower cylindrical auger extend into the feeding port; and the front end of the lower cylindrical auger is connected with a lower cone auger through a flexible shaft in a transmitting way, wherein the lower cone auger opens horizontally towards one side of the upper cylindrical auger. The portable combined grain harvester solves the problems that the existing small combined grain harvester cannot work in the hilly areas, and the portable combined grain harvester has a good threshing effect and ensures that the grain contains less impurities.