This is an all-in-one radio frequency identification system for goods inventory and sale management, comprising at least one tag, an antenna unit and a multi-port reader comprising a micro control unit, a reader and a multiplexer. The tag is attached on each article. The antenna unit is RF coupled to the tag. The multiplexer built-in the multi-port reader is electrically coupled to the antenna unit. The reader built-in the multi-port reader is capable of transmitting RF signals, accessing commands and receiving tag signals from the multiplexer. The micro control unit is electrically coupled to the multiplexer and the reader to receive and process the reading signal and provide inventory and sale management functions and applications. Therefore, the all-in-one radio frequency identification system provides not only inventory and anti-theft functions but also information for consumer behavior research, and capable of doing stand alone operations.