An axial flow impeller, comprising: a central hub, comprising a base plate and a stacking sidewall disposed at an edge of the base plate, wherein a first edge of the stacking sidewall extending axially is provided with a plurality of first convex portions, and a plurality of first concave portions are respectively provided between every two adjacent first convex portions of the plurality of first convex portions, wherein a second edge of the stacking sidewall extending axially is provided with a plurality of second convex portions, and a plurality of second concave portions are respectively disposed between every two adjacent second convex portions of the plurality of second convex portions, wherein the plurality of first convex portions are in one-to-one correspondence with the plurality of second concave portions in the axial direction, and the plurality of first concave portions are in one-to-one correspondence with the plurality of second convex portions in the axial direction; and a plurality of blades, disposed along an external surface of the stacking sidewall, and an edge of each of the plurality of blades connecting to the stacking sidewall extends from an edge of one of the plurality of first convex portions to an edge of an adjacent second convex portion; wherein the base plate comprises a mounting portion and an annular portion disposed at a periphery of the mounting portion, wherein the mounting portion is provided with a mounting hole, and wherein a first and second surface of the annular portion are provided with support ribs; wherein the support ribs comprise a first support rib group disposed on the first surface of the annular portion and a second support rib group disposed on the second surface of the annular portion, and wherein the first support rib group and the second support rib group are of different shapes; characterized in that: a plurality of first support ribs of the first support rib group extend in a rotational direction, and heights of the plurality of first support ribs extending in the axial direction gradually increase from a first end close to the mounting portion to a second end away from the mounting portion. a central hub, comprising a base plate and a stacking sidewall disposed at an edge of the base plate, wherein a first edge of the stacking sidewall extending axially is provided with a plurality of first convex portions, and a plurality of first concave portions are respectively provided between every two adjacent first convex portions of the plurality of first convex portions, wherein a second edge of the stacking sidewall extending axially is provided with a plurality of second convex portions, and a plurality of second concave portions are respectively disposed between every two adjacent second convex portions of the plurality of second convex portions, wherein the plurality of first convex portions are in one-to-one correspondence with the plurality of second concave portions in the axial direction, and the plurality of first concave portions are in one-to-one correspondence with the plurality of second convex portions in the axial direction; and a plurality of blades, disposed along an external surface of the stacking sidewall, and an edge of each of the plurality of blades connecting to the stacking sidewall extends from an edge of one of the plurality of first convex portions to an edge of an adjacent second convex portion; wherein the base plate comprises a mounting portion and an annular portion disposed at a periphery of the mounting portion, wherein the mounting portion is provided with a mounting hole, and wherein a first and second surface of the annular portion are provided with support ribs; wherein the support ribs comprise a first support rib group disposed on the first surface of the annular portion and a second support rib group disposed on the second surface of the annular portion, and wherein the first support rib group and the second support rib group are of different shapes; characterized in that: a plurality of first support ribs of the first support rib group extend in a rotational direction, and heights of the plurality of first support ribs extending in the axial direction gradually increase from a first end close to the mounting portion to a second end away from the mounting portion.