A TDD radio unit and a real-time RX supervision method used therein are provided. The method comprises steps of: setting the radio unit into an RX supervision status in a TX timeslot, wherein the setting comprises: connecting a TX observation module in the radio unit to a termination port of a Transmit/Receive (TR) switch in the radio unit; and setting all components in the RX path in a power-on status; detecting a gain of the TX observation module by means of a signal from the TR switch passing through the TX observation module and a gain of the RX path by means of a TX leakage signal passing through the RX path; calculating a gain difference between the TX observation module and the RX path; and comparing the calculated gain difference with a preset gain difference to determine a state of the RX path. With the TDD radio unit and RX supervision method, the TX leakage signal is used, and thus no extra simulation source is need. Furthermore, a real time supervision is performed.