The disclosure discloses a method and a system for transmitting location data. The method comprises at least one step of that: the location data is transmitted between a first terminal and a second terminal; the location data is transmitted between a first location server and a second location server; and the location data is transmitted between a third terminal and a third location server, wherein the location data comprises: assistance location data and/or position data. According to the technical solution provided by the disclosure, the location function between two terminals supporting Security User Plane Location (SUPL) can be realized, and some novel assistance location data can be transmitted.