An electronic cigarette, comprising: a housing; a mouthpiece arranged at a first end of the housing; a simulate cigarette end arranged at an opposite second end of the housing; a battery module received in the housing; a liquid cup arranged in the housing, and being configured for containing tobacco liquid; an atomizing unit arranged in the housing, and electrically connected with the battery module, the atomizing unit being configured for atomizing the tobacco liquid to form aerosol; wherein the liquid cup comprises a cup body and a resilient plug at an end of the cup body, the resilient plug is capable of being pierced by a needle of an injector, and capable of restoring to a sealed state after the needle of the injector is removed, wherein the resilient plug is arranged at a first end of the cup body facing the mouthpiece, wherein the atomizing unit includes a liquid conducting body and a heating wire wound around the liquid conducting body, the liquid conducting body is configured for absorbing the tobacco liquid for atomization, and the heating wire is configured for heating the tobacco liquid, the electronic cigarette further comprising a liquid permeating layer at an opposite second end of the cup body, wherein the liquid conducting body is in contact with the liquid permeating layer, so that the liquid conducting body absorbs the tobacco liquid from the liquid permeating layer, wherein the liquid conducting body is U-shaped, includes a main body and two liquid absorbing parts connected at two ends of the main body, the heating wire is wound around the main body, and the liquid absorbing parts contact with the liquid permeating layer, the electronic cigarette further comprising a cover body at the opposite second end of the cup body, wherein the cover body is formed on top of the liquid permeating layer, and defines a plurality of through holes, so that the tobacco liquid in the liquid cup can flow to the liquid permeating layer, the electronic cigarette further comprising a base holder and an O-shaped ring, wherein the base holder is received in the housing, and arranged between the battery module and the liquid cup, the base holder defines an annular groove in a sidewall, and the O-shaped ring is engaged in the annular groove, characterized in that the electronic cigarette further comprises a silicone holder arranged on the base holder, wherein the silicone holder is configured for supporting the liquid conducting body. a housing; a mouthpiece arranged at a first end of the housing; a simulate cigarette end arranged at an opposite second end of the housing; a battery module received in the housing; a liquid cup arranged in the housing, and being configured for containing tobacco liquid; an atomizing unit arranged in the housing, and electrically connected with the battery module, the atomizing unit being configured for atomizing the tobacco liquid to form aerosol; wherein the liquid cup comprises a cup body and a resilient plug at an end of the cup body, the resilient plug is capable of being pierced by a needle of an injector, and capable of restoring to a sealed state after the needle of the injector is removed, wherein the resilient plug is arranged at a first end of the cup body facing the mouthpiece, wherein the atomizing unit includes a liquid conducting body and a heating wire wound around the liquid conducting body, the liquid conducting body is configured for absorbing the tobacco liquid for atomization, and the heating wire is configured for heating the tobacco liquid, the electronic cigarette further comprising a liquid permeating layer at an opposite second end of the cup body, wherein the liquid conducting body is in contact with the liquid permeating layer, so that the liquid conducting body absorbs the tobacco liquid from the liquid permeating layer, wherein the liquid conducting body is U-shaped, includes a main body and two liquid absorbing parts connected at two ends of the main body, the heating wire is wound around the main body, and the liquid absorbing parts contact with the liquid permeating layer, the electronic cigarette further comprising a cover body at the opposite second end of the cup body, wherein the cover body is formed on top of the liquid permeating layer, and defines a plurality of through holes, so that the tobacco liquid in the liquid cup can flow to the liquid permeating layer, the electronic cigarette further comprising a base holder and an O-shaped ring, wherein the base holder is received in the housing, and arranged between the battery module and the liquid cup, the base holder defines an annular groove in a sidewall, and the O-shaped ring is engaged in the annular groove, characterized in that the electronic cigarette further comprises a silicone holder arranged on the base holder, wherein the silicone holder is configured for supporting the liquid conducting body.