The embodiment of the invention provides a composite antenna assembly and an electronic device, which relate to the technical field of antennas. The composite antenna assembly includes a feed point, agrounding point, a first radiator of a first antenna in a first frequency band, and a second radiator of a second antenna in a second frequency band. The metal frame has an opening, the distance between the opening and the grounding point on the metal frame is a first distance, and the metal frame between the opening and the grounding point forms the first radiator; and the feed point is betweenthe grounding point and the opening and at the second distance of the opening, and the metal frame between the feed point and the grounding point forms the second radiator. Antennas of different frequency bands can be compounded, the number of antennas is not increased, and the overall performance of the antenna is improved.