A button assembly of the present invention is configured in a communication equipment. The button assembly includes a button, a tray and at least an elastic arm. A side of the button is recessed inward to form a holding space. At least an inner side wall of the holding space is recessed to form a clamping groove. The tray is disposed in the holding space. The elastic arm has a fixing portion mounted on a side wall of the tray. The fixing portion is extended frontward and is protruded outward to form a contact part. The contact part is extended frontward and outward to form a clamping part disposed in the clamping groove. The clamping groove and the elastic arm are disposed to provide the button and the tray to be fixed or disengaged, achieving an effect of saving space in assembling of internal components of the communication equipment.