A neckband earphone is provided, and a method, a system and a device for switching functions of the neckband earphone are provided. A key is provided on each of a left portion and a right portion of a neckband of the neckband earphone. The neckband is provided with a detector and a processor connected with the detector. The detector is configured to detect and determine a wearing orientation of the neckband earphone. The processor is configured to determine a function of the key on the left portion and a function of the key on the right portion based on the wearing orientation, to control key functions on a left side and a right side of a human body wearing the neckband earphone to remain unchanged for different wearing orientations.