An atomizer, comprising: a shell defining a smoke outlet , a liquid cavity and an atomizing chamber , wherein the liquid cavity is capable of storing a fluid to be vaporized, the smoke outlet communicates with environment outside of the shell ; and a heating assembly separating the smoke outlet and the liquid cavity from the atomizing chamber , and comprising a liquid guiding member , a cover , a heating component and a sealing component engaged between the cover and the liquid guiding member ; wherein the cover is an integral structure defining a liquid tunnel and a smoke tunnel , the liquid tunnel communicates with the liquid cavity and extends to the first surface of the liquid guiding member , the cover defines an accommodating space , an opening of the accommodating space faces towards the liquid guiding member , and the liquid guiding member is partially received in the accommodating space , the cover covers the first surface of the liquid guiding member and one portion of the second surface of the liquid guiding member , another portion of the second surface of the liquid guiding member is exposed in the atomizing chamber ; the liquid guiding member is configured to transport the fluid from the liquid tunnel to the atomizing chamber , and to heat the fluid to generate smoke in the atomizing chamber ; the smoke outlet communicates with the atomizing chamber via the smoke tunnel , such that the generated smoke is allowed to exit from the smoke tunnel and further enter the smoke outlet ; the heating component is connected with the liquid guiding member , and is configured to heat the liquid guiding member ; and the sealing component defines a through hole extending from the liquid tunnel to the first surface of the liquid guiding member . a shell defining a smoke outlet , a liquid cavity and an atomizing chamber , wherein the liquid cavity is capable of storing a fluid to be vaporized, the smoke outlet communicates with environment outside of the shell ; and a heating assembly separating the smoke outlet and the liquid cavity from the atomizing chamber , and comprising a liquid guiding member , a cover , a heating component and a sealing component engaged between the cover and the liquid guiding member ; wherein the cover is an integral structure defining a liquid tunnel and a smoke tunnel , the liquid tunnel communicates with the liquid cavity and extends to the first surface of the liquid guiding member , the cover defines an accommodating space , an opening of the accommodating space faces towards the liquid guiding member , and the liquid guiding member is partially received in the accommodating space , the cover covers the first surface of the liquid guiding member and one portion of the second surface of the liquid guiding member , another portion of the second surface of the liquid guiding member is exposed in the atomizing chamber ; the liquid guiding member is configured to transport the fluid from the liquid tunnel to the atomizing chamber , and to heat the fluid to generate smoke in the atomizing chamber ; the smoke outlet communicates with the atomizing chamber via the smoke tunnel , such that the generated smoke is allowed to exit from the smoke tunnel and further enter the smoke outlet ; the heating component is connected with the liquid guiding member , and is configured to heat the liquid guiding member ; and the sealing component defines a through hole extending from the liquid tunnel to the first surface of the liquid guiding member . <EOS>