An in-ear earphone includes a face shell for mounting an earphone cable and a bottom shell provided with an ear cap, and the face shell and the bottom shell are detachably fixed to each other. A loudspeaker and an air valve are arranged at the bottom shell, and the bottom shell is further provided with a sound transmission channel. One end of the sound transmission channel is in communication with an inner ear canal located at a side where the ear cap is located, and another end of the sound transmission channel is connected to a sealing plug formed by the air valve and the loudspeaker. One end of the air valve is connected to the sound transmission channel, and another end of the air valve is connected to an outer ear canal, to control the communication between the sound transmission channel and the outer ear canal.