The invention discloses a multi-antenna feed network detection system and device, and relates to the technical field of communication. The system comprises multiple radio frequency identification (RFID) tags respectively located in each antenna coverage area of a multi-antenna feed network, a first RFID reader-writer, and a detection device, wherein the first RFID reader-writer is used for transmitting RFID query signals to the multiple RFID tags through a to-be-detected multi-antenna feed network; the RFID tags are used for returning tag identifiers (ID) to the first RFID reader-writer after receiving the RFID query signals from the first RFID reader-writer; the first RFID reader-writer is further used for receiving the tag IDs returned by the RFID tags; and the detection device is used for determining branches of the tag IDs corresponding to RFID tags, which are not received by the first RFID reader-writer, to be abnormal branches in the multi-antenna feed network. The multi-antenna feed network detection system and device can determine the abnormal branches in the multi-antenna feed network and can help subsequent maintenance.