The invention belongs to a preparation technology of tritium labeled compounds, and in particular relates to a tritium labeling reaction device. Reaction flasks, three uranium powder bottles and a vacuum pump are connected into a closed system through metal pipes and valves, and are connected to a main pipeline formed by the metal pipes, wherein the three uranium powder bottles are a tritium storage uranium powder bottle, a tritium recovery uranium powder bottle and a spare uranium powder bottle respectively, are arranged in parallel, are connected with the main pipeline, and are provided with a control valve respectively; a surge flask and a cold trap are arranged on the metal pipe, connected with the vacuum pump, of the main pipeline. The device is completely connected through components such as the metal pipes and the vales in clamping and sleeving ways, so that the vacuum tightness of the system is ensured, and the tritium labeling efficiency, stability and safety are improved.