A RFID system for checking medical items includes a processing unit; two RFID readers connected with the processing unit; at least an antenna connected to each of the RFID readers; and a plurality of RFID tags being respectively attached to a plurality of medical items. The RFID tags are configured to store identification codes that respectively and uniquely correspond to the medical items that the RFID tags are attached to. The RFID readers are configured to respectively read the identification codes of the medical items from the RFID tags through the antennas before and after a surgical operation and send the identification codes to the processing unit. The processing unit is configured to receive the identification codes and determine the completeness of the medical items based on the received identification codes. A method for checking medical items with the RFID system is also provided.