An atomizer includes: a liquid storage cavity; a ventilation channel; and a pressure relief micro-channel. The liquid storage cavity stores an atomization substrate. One end of the ventilation channel is communicated with the liquid storage cavity, and another end of the ventilation channel is communicated with an external environment. One end of the pressure relief micro-channel is communicated with the liquid storage cavity, and another end of the pressure relief micro-channel is communicated with the external environment. A flow resistance of a fluid in the pressure relief micro-channel is greater than or equal to a flow resistance of a fluid in the ventilation channel.