Abstract: An indoor positioning system includes: a wireless network device, configured to receive a positioning request initiated by positioning tag, and send a handshake communication request; a positioning headend, configured to communicate with the wireless network device and the positioning tag according to the handshake communication request, and collect radio wave signals sent by the positioning tag, and calculate the phase information of the positioning tag according to the radio wave signal; a positioning unit, configured to calculate position coordinate information of the positioning tag according to the phase information, thereby improving the positioning accuracy and reducing the cost.