An atomizer for an electronic cigarette comprising: an atomizing sleeve, the atomizing sleeve defining an air outlet at a top end thereof; a liquid chamber sealed in the atomizing sleeve; and an atomizing assembly arranged at a bottom end of the sleeve, the atomizing assembly comprising: a hollow fixing holder fixedly connected the bottom part of the atomizing sleeve; a transmission component, passing through the fixing holder, and being movable along an axial direction thereof relative to the fixing holder; a seal cover fixedly connected with the transmission component, the seal cover being movable with the transmission component between a first position where a liquid passage is formed between the seal cover and the fixing holder, and a second position where the liquid passage is closed; an elastic element configured for storing energy when the liquid passage is open, and for driving the transmission component to move downwards and bringing the seal cover to move downwards to close the liquid passage; an air pipe, a first end of the air pipe being fixedly connected with the seal cover, an opposite second end of the air pipe extending to the air outlet; and a heating component having a liquid conducting element and a heating element, the liquid conducting element being configured for absorbing tobacco liquid flowing from the liquid passage, the heating element being configured for heating the absorbed tobacco liquid to vaporize, characterized in that the elastic element is sandwiched between the transmission component and the fixing holder. an atomizing sleeve, the atomizing sleeve defining an air outlet at a top end thereof; a liquid chamber sealed in the atomizing sleeve; and an atomizing assembly arranged at a bottom end of the sleeve, the atomizing assembly comprising: a hollow fixing holder fixedly connected the bottom part of the atomizing sleeve; a transmission component, passing through the fixing holder, and being movable along an axial direction thereof relative to the fixing holder; a seal cover fixedly connected with the transmission component, the seal cover being movable with the transmission component between a first position where a liquid passage is formed between the seal cover and the fixing holder, and a second position where the liquid passage is closed; an elastic element configured for storing energy when the liquid passage is open, and for driving the transmission component to move downwards and bringing the seal cover to move downwards to close the liquid passage; an air pipe, a first end of the air pipe being fixedly connected with the seal cover, an opposite second end of the air pipe extending to the air outlet; and a heating component having a liquid conducting element and a heating element, the liquid conducting element being configured for absorbing tobacco liquid flowing from the liquid passage, the heating element being configured for heating the absorbed tobacco liquid to vaporize, characterized in that the elastic element is sandwiched between the transmission component and the fixing holder. a hollow fixing holder fixedly connected the bottom part of the atomizing sleeve; a transmission component, passing through the fixing holder, and being movable along an axial direction thereof relative to the fixing holder; a seal cover fixedly connected with the transmission component, the seal cover being movable with the transmission component between a first position where a liquid passage is formed between the seal cover and the fixing holder, and a second position where the liquid passage is closed; an elastic element configured for storing energy when the liquid passage is open, and for driving the transmission component to move downwards and bringing the seal cover to move downwards to close the liquid passage; an air pipe, a first end of the air pipe being fixedly connected with the seal cover, an opposite second end of the air pipe extending to the air outlet; and a heating component having a liquid conducting element and a heating element, the liquid conducting element being configured for absorbing tobacco liquid flowing from the liquid passage, the heating element being configured for heating the absorbed tobacco liquid to vaporize, characterized in that the elastic element is sandwiched between the transmission component and the fixing holder.