Abstract: An in-ear earphone with a capacitive sensing function is provided. The earphone includes a case, a speaker, a circuit board, and a capacitive sensing unit. The case has an extension tube and an accommodating portion. An ear tip is sleeved on the extension tube. The accommodating portion accommodates the speaker, the circuit board, and the capacitive sensing unit. A sound emitting surface of the speaker faces the extension tube. The circuit board is electrically connected to the speaker, and a sensing chip is disposed on the circuit board. The capacitive sensing unit includes a sensor and a conducting element. The sensor is electrically connected to the sensing chip through the conducting element. When the extension tube is inserted into an ear canal of a user, the sensor returns a sensing signal to the sensing chip, and the sensing chip sends a control signal to control sound output of the speaker.