Embodiments of the present disclosure disclose a positioning information transmission method, a related device, and a system. The positioning information transmission method includes: determining an uplink subframe for carrying an uplink signal and a downlink subframe for carrying a downlink signal; determining first measurement information and second measurement information; and sending the first measurement information and the second measurement information to a positioning server, for locating a terminal device by the positioning server. Positioning accuracy can be improved by using the embodiments of the present disclosure.