A dust cup, comprising a cup body and a two-stage dust-air separation structure arranged inside the cup body, an air inlet and an air outlet are arranged in a sidewall of the cup body, wherein, the two-stage dust-air separation structure comprises a cyclone separator and a spiral dust-air separation device, wherein the cyclone separator comprises a cyclone housing for a first stage dust-air separation and a second-stage cyclone barrel arranged inside the cyclone housing, a space between the cup body and the cyclone housing of the two-stage dust-air separation structure forms a first-stage dust collecting barrel, a gap is provided between the second-stage cyclone barrel and an inner wall of the cyclone housing, and the gap is configured to form an air-intake duct for introducing dusty air after going through the first stage dust-air separation; the spiral dust-air separation device is arranged at a barrel opening of the second-stage cyclone barrel and comprises a spiral impeller configured to generate a second-stage cyclone, an opening connected to a second-stage dust collecting space is further provided at a barrel bottom of the second-stage cyclone barrel; a partition plate is arranged inside the cup body, a center of the partition plate extends downward to form an opening, a return-air dust guard is arranged on the extended opening and above the spiral impeller, the return-air dust guard is fixedly connected to an edge of the opening by a plurality of cyclone ribs arranged on a periphery of the return-air dust guard, such that the air after going through the second stage dust-air separation is extracted by the negative pressure via gaps between the cyclone ribs, to realize a second stage dust-air separation; wherein, the cyclone separator further comprises: an inverted dust retaining barrel arranged inside the second-stage cyclone barrel, a gap is provided between the dust retaining barrel and the second-stage cyclone barrel, and the gap is configured to form a second-stage dust-air separation duct. the two-stage dust-air separation structure comprises a cyclone separator and a spiral dust-air separation device, wherein the cyclone separator comprises a cyclone housing for a first stage dust-air separation and a second-stage cyclone barrel arranged inside the cyclone housing, a space between the cup body and the cyclone housing of the two-stage dust-air separation structure forms a first-stage dust collecting barrel, a gap is provided between the second-stage cyclone barrel and an inner wall of the cyclone housing, and the gap is configured to form an air-intake duct for introducing dusty air after going through the first stage dust-air separation; the spiral dust-air separation device is arranged at a barrel opening of the second-stage cyclone barrel and comprises a spiral impeller configured to generate a second-stage cyclone, an opening connected to a second-stage dust collecting space is further provided at a barrel bottom of the second-stage cyclone barrel; a partition plate is arranged inside the cup body, a center of the partition plate extends downward to form an opening, a return-air dust guard is arranged on the extended opening and above the spiral impeller, the return-air dust guard is fixedly connected to an edge of the opening by a plurality of cyclone ribs arranged on a periphery of the return-air dust guard, such that the air after going through the second stage dust-air separation is extracted by the negative pressure via gaps between the cyclone ribs, to realize a second stage dust-air separation; wherein, the cyclone separator further comprises: an inverted dust retaining barrel arranged inside the second-stage cyclone barrel, a gap is provided between the dust retaining barrel and the second-stage cyclone barrel, and the gap is configured to form a second-stage dust-air separation duct.