The utility model provides a containment atmospheric radiation 18F detection device. Containment, wherein the sampling pipe and the sample return pipe are arranged on the containment vessel; the sampling connecting valve and the sample return connecting valve are arranged on the sampling pipe and the sample return pipe; wherein the 18F detection assembly and the sampling pump are arranged at the front end of the sample return connecting valve, the 18F detection assembly comprises a shielding body, a main detector, a coincidence detector and a filtering device, the main detector, the coincidence detector and the filtering device are arranged in the shielding body, the main detector and the coincidence detector are oppositely arranged, and the middle parts of the main detector and the coincidence detector are respectively connected with the filtering device; according to the utility model, the 18F detection device is adopted, and whether the pressure boundary of the primary loop leaks ornot can be judged by continuously monitoring the specific radioactivity concentration of 18F in the containment vessel.