An electronic cigarette, comprising: a mouthpiece subassembly; an e-liquid charging subassembly; an atomizing subassembly; and a base subassembly; wherein: the mouthpiece subassembly is mounted on the e-liquid charging subassembly; the atomizing subassembly is screwed upon the base subassembly; the base subassembly is connected to the e-liquid charging subassembly; the e-liquid charging subassembly comprises a second seal ring, a sleeve ring, a third seal ring, and a glass tube; the second seal ring is disposed on the sleeve ring; the third seal ring is disposed in a bottom of the sleeve ring; the glass tube is connected to one end of the sleeve ring, and the other end of the sleeve ring is connected to the mouthpiece subassembly; the atomizing subassembly comprises a fourth seal ring, a limit cover, a silica ring, a first cotton, a heating wire, a second cotton, a fixed ring, a first insulation ring, and a first joint; the heating wire is wrapped by the second cotton and disposed in the fixed ring; the limit cover limits the heating wire, the fourth seal ring is disposed on the limit cover; the first insulation ring and the first joint are disposed on a bottom of the fixed ring; the first cotton wraps the fixed ring; the first cotton and the fixed ring are inserted in the limit cover; the fourth seal ring and the silica ring are disposed at two ends of the limit cover, respectively; the base subassembly comprises a fifth seal ring, a press part, sixth seal rings, a vapor adjusting ring, a base, a second insulation ring, and a second joint; the second insulation ring and the second joint are disposed in the base; the sixth seal rings are disposed on two ends of the base, respectively; the press part presses on the base; and the fifth seal ring is fixed on the press part; and the vapor adjusting ring comprises a circumferential wall which is provided with a transverse hole and/or a longitudinal hole; characterised in that: the e-liquid charging subassembly further comprises an e-liquid charging member, in which the sleeve ring is embedded; the mouthpiece subassembly comprises a cigarette holder and a first seal ring; the first seal ring is tightly coupled to the cigarette holder, the cigarette holder is detachably disposed on the e-liquid charging subassembly so that the mouthpiece subassembly is detachably mounted on the e-liquid charging subassembly, and the cigarette holder is connected to the sleeve ring of the e-liquid charging subassembly; the vapor adjusting ring comprises a threaded portion; and the vapor adjusting ring is screwed on the base to be in threaded connection to the base through the threaded portion; and by rotation of the vapor adjusting ring relative to the base, an output volume of vapor is adjustable. a mouthpiece subassembly; an e-liquid charging subassembly; an atomizing subassembly; and a base subassembly; the mouthpiece subassembly is mounted on the e-liquid charging subassembly; the atomizing subassembly is screwed upon the base subassembly; the base subassembly is connected to the e-liquid charging subassembly; the e-liquid charging subassembly comprises a second seal ring, a sleeve ring, a third seal ring, and a glass tube; the second seal ring is disposed on the sleeve ring; the third seal ring is disposed in a bottom of the sleeve ring; the glass tube is connected to one end of the sleeve ring, and the other end of the sleeve ring is connected to the mouthpiece subassembly; the atomizing subassembly comprises a fourth seal ring, a limit cover, a silica ring, a first cotton, a heating wire, a second cotton, a fixed ring, a first insulation ring, and a first joint; the heating wire is wrapped by the second cotton and disposed in the fixed ring; the limit cover limits the heating wire, the fourth seal ring is disposed on the limit cover; the first insulation ring and the first joint are disposed on a bottom of the fixed ring; the first cotton wraps the fixed ring; the first cotton and the fixed ring are inserted in the limit cover; the fourth seal ring and the silica ring are disposed at two ends of the limit cover, respectively; the base subassembly comprises a fifth seal ring, a press part, sixth seal rings, a vapor adjusting ring, a base, a second insulation ring, and a second joint; the second insulation ring and the second joint are disposed in the base; the sixth seal rings are disposed on two ends of the base, respectively; the press part presses on the base; and the fifth seal ring is fixed on the press part; and the vapor adjusting ring comprises a circumferential wall which is provided with a transverse hole and/or a longitudinal hole; the e-liquid charging subassembly further comprises an e-liquid charging member, in which the sleeve ring is embedded; the mouthpiece subassembly comprises a cigarette holder and a first seal ring; the first seal ring is tightly coupled to the cigarette holder, the cigarette holder is detachably disposed on the e-liquid charging subassembly so that the mouthpiece subassembly is detachably mounted on the e-liquid charging subassembly, and the cigarette holder is connected to the sleeve ring of the e-liquid charging subassembly; the vapor adjusting ring comprises a threaded portion; and the vapor adjusting ring is screwed on the base to be in threaded connection to the base through the threaded portion; and by rotation of the vapor adjusting ring relative to the base, an output volume of vapor is adjustable.