A dust cup assembly, comprising: a cup casing; a device housing configured to be the shape of a tube and disposed in the cup casing; and a negative pressure device located within the device housing and enabling dusty air to enter the dust removal chamber for dust and air separation, wherein an outer end face of the device housing at an axial side thereof abuts against or extends beyond a partial inner surface of the cup casing, and a first cyclone separating member is disposed in a dust removal chamber that is defined between an inner surface of the cup casing and an outer peripheral face of the device housing and surrounds the device housing along a circumferential direction of the device housing; wherein the negative pressure device includes a fan and a motor connected sequentially along the axial direction of the device housing, and the motor is spaced apart from the first cyclone separating member in the axial direction of the device housing, characterized in that, the device housing includes a first tube segment, a transition tube segment and a second tube segment which are sequentially connected together along the axial direction of the device housing, and wherein a maximum diameter of the first tube segment is smaller than a minimum diameter of the second tube segment, and wherein a first portion of the dust removal chamber radially opposite to the first tube segment has a larger capacity than a second portion of the dust removal chamber radially opposite to the second tube segment, and a first portion of the air exhaust chamber radially opposite to the second tube segment has a larger capacity than a second portion of the air exhaust chamber radially opposite to the first tube segment; and wherein the first cyclone separating member is arranged opposite to the first tube segment and the transition tube segment, wherein the negative pressure device is arranged opposite to the second tube segment, and wherein the first cyclone separating member is integrally molded to an outer peripheral wall of the first tube segment and an outer peripheral wall of the transition tube segment, and the first cyclone separating member having plurality of cyclones spliced by a plurality of straight tube segments and a plurality of tapered tube segments; wherein the first tube segment and the second tube segment both are configured as the straight tube segments, and the transition tube segment is configured as a divergent tube segment. a cup casing; a device housing configured to be the shape of a tube and disposed in the cup casing; and a negative pressure device located within the device housing and enabling dusty air to enter the dust removal chamber for dust and air separation, wherein an outer end face of the device housing at an axial side thereof abuts against or extends beyond a partial inner surface of the cup casing, and a first cyclone separating member is disposed in a dust removal chamber that is defined between an inner surface of the cup casing and an outer peripheral face of the device housing and surrounds the device housing along a circumferential direction of the device housing; wherein the negative pressure device includes a fan and a motor connected sequentially along the axial direction of the device housing, and the motor is spaced apart from the first cyclone separating member in the axial direction of the device housing, characterized in that, the device housing includes a first tube segment, a transition tube segment and a second tube segment which are sequentially connected together along the axial direction of the device housing, and wherein a maximum diameter of the first tube segment is smaller than a minimum diameter of the second tube segment, and wherein a first portion of the dust removal chamber radially opposite to the first tube segment has a larger capacity than a second portion of the dust removal chamber radially opposite to the second tube segment, and a first portion of the air exhaust chamber radially opposite to the second tube segment has a larger capacity than a second portion of the air exhaust chamber radially opposite to the first tube segment; and wherein the first cyclone separating member is arranged opposite to the first tube segment and the transition tube segment, wherein the negative pressure device is arranged opposite to the second tube segment, and wherein the first cyclone separating member is integrally molded to an outer peripheral wall of the first tube segment and an outer peripheral wall of the transition tube segment, and the first cyclone separating member having plurality of cyclones spliced by a plurality of straight tube segments and a plurality of tapered tube segments; wherein the first tube segment and the second tube segment both are configured as the straight tube segments, and the transition tube segment is configured as a divergent tube segment.