A dual-frequency coaxial earphone includes a dynamic transducer, a cover and a second transducer. The dynamic transducer includes a supporting structure and a vibrating diaphragm mounted to the supporting structure. The cover covers on the supporting structure, so that the cover and the supporting structure define a sound adjusting chamber therein. The cover includes an adjusting orifice communicating with the sound adjusting chamber. The second transducer is adapted to the cover and the second transducer has a first side facing toward the sound adjusting chamber. The sound adjusting chamber is located between the vibrating diaphragm and the second transducer.