A back clip fixture of a receiver and transmitter device assembled by a back clip and a receiver and transmitter device is characterized that a concave slot is respectively disposed at positions opposite two sides of the detachment seat for facilitating the mounting and dismounting of a joint seat piece; more especially, the lower positioning piece has a slot location for fitly assembling an upper positioning piece; furthermore, the upper positioning piece has a notch disposed thereby providing a larger space for a resilient piece to separate from a positioning slot so as to increase the detachment effect.