An antenna unit and a terminal device are provided. The antenna unit includes a target metal groove, M feed portions arranged at the bottom of the target metal groove, M coupling bodies and a first insulator which are arranged in the target metal groove, and at least two radiating bodies borne by the first insulator, wherein the M feed portions are insulated from the target metal groove, the M coupling bodies are located between the bottom of the target metal groove and the first insulator, each of the M feed portions is electrically connected to one coupling body respectively, each of the M coupling bodies is coupled with the at least two radiating bodies and the target metal groove, different radiating bodies have different resonance frequencies, and M is a positive integer.