The technologies used in the indoor localization mainly contain infrared propagation technique, IEEE 802.11 Wireless LAN, Wireless Sensor Networks(WSNs), and ultrasonic localization. Instead, Radio Frequency Identification(RFID) technique, with its numerous advantages of reasonable system cost, excellent location accuracy, strong anti-interference, contactless communications, convenient deployment and carry, has been widely used in indoor localization. From the point of RFID tags used in the indoor localization, the primary RFID-based indoor localization techniques are classified into three categories, namely, passive localization, active localization, and semi-passive localization. The analysis about the state of the art of the primary RFID-based localization algorithms is presented in detail, as well as the advantages and disadvantages of each technique.