Disclosed is an earphone. The earphone includes an end cap portion, a housing portion, an adapter portion, an ear hook portion, and a loudspeaker. The end cap portion, the housing portion, and the adapter portion are connected in sequence to form a three-section structure. In the three-section structure, two sides of the housing portion are provided with a first opening and a second opening, respectively. The end cap portion covers the first opening, and the adapter portion covers the second opening. The housing portion forms a cylindrical structure with openings at two ends. The end cap portion, the housing portion, and the adapter portion can be quickly assembled along a major axis direction.