A heating core, comprising a conductor and an e-liquid absorber;wherein: the conductor comprises a cylindrical wall having an inner cylindrical surface, and a cavity confined by the inner cylindrical surface; and the e-liquid absorber is disposed in the cavity; the conductor further comprises a channel communicating with the cavity, a plurality of e-liquid inlets communicating with the cavity and opposite to the e-liquid absorber, a first hollow tube, and a second hollow tube; the first hollow tube and the second hollow tube are integrally formed; the first hollow tube has an elliptical cross section, and the second hollow tube has a round cross section; one end of the first hollow tube shrinks and extends axially to form the second hollow tube; the cavity is formed in the first hollow tube; and the plurality of e-liquid inlets is circumferentially disposed on the first hollow tube; the channel is disposed in the second hollow tube and communicates with the cavity; the e-liquid absorber is molded to the conductor; the e-liquid absorber comprises an outer cylindrical wall, two inner cylindrical walls, and two through holes each confined by one of the two inner cylindrical walls; the outer cylindrical wall of the e-liquid absorber is attached to the inner cylindrical surface of the conductor, and the heating core is free of a gap between the outer cylindrical wall of the e-liquid absorber and the inner cylindrical surface of the conductor; and two heating elements are embedded in the e-liquid absorber adjacent to the two inner cylindrical walls, respectively; and the two heating elements are spirally wrapped around the two inner cylindrical walls, respectively. the conductor comprises a cylindrical wall having an inner cylindrical surface, and a cavity confined by the inner cylindrical surface; and the e-liquid absorber is disposed in the cavity; the conductor further comprises a channel communicating with the cavity, a plurality of e-liquid inlets communicating with the cavity and opposite to the e-liquid absorber, a first hollow tube, and a second hollow tube; the first hollow tube and the second hollow tube are integrally formed; the first hollow tube has an elliptical cross section, and the second hollow tube has a round cross section; one end of the first hollow tube shrinks and extends axially to form the second hollow tube; the cavity is formed in the first hollow tube; and the plurality of e-liquid inlets is circumferentially disposed on the first hollow tube; the channel is disposed in the second hollow tube and communicates with the cavity; the conductor further comprises a channel communicating with the cavity, a plurality of e-liquid inlets communicating with the cavity and opposite to the e-liquid absorber, a first hollow tube, and a second hollow tube; the first hollow tube and the second hollow tube are integrally formed; the first hollow tube has an elliptical cross section, and the second hollow tube has a round cross section; one end of the first hollow tube shrinks and extends axially to form the second hollow tube; the cavity is formed in the first hollow tube; and the plurality of e-liquid inlets is circumferentially disposed on the first hollow tube; the channel is disposed in the second hollow tube and communicates with the cavity; the e-liquid absorber is molded to the conductor; the e-liquid absorber comprises an outer cylindrical wall, two inner cylindrical walls, and two through holes each confined by one of the two inner cylindrical walls; the outer cylindrical wall of the e-liquid absorber is attached to the inner cylindrical surface of the conductor, and the heating core is free of a gap between the outer cylindrical wall of the e-liquid absorber and the inner cylindrical surface of the conductor; and two heating elements are embedded in the e-liquid absorber adjacent to the two inner cylindrical walls, respectively; and the two heating elements are spirally wrapped around the two inner cylindrical walls, respectively.