An atomizer includes: a housing, defining a first airflow passage through an inlet end and an outlet end; a liquid storage chamber, disposed within the housing; an atomizing assembly, disposed in a path of the first airflow passage, the atomizing assembly is in fluid connection with the liquid storage chamber; a sealing element, including a sealing body and an air compensating valve, the sealing body is configured to form a seal between the housing and the atomizing assembly, the air compensating valve includes a first side and a second side opposite to each other, the first side is located within the liquid storage chamber, the second side communicates with external air. The air compensating valve is opened when a pressure of the external air on the second side is greater than a pressure in the liquid storage chamber on the first side.