A method of performing a SET-to-SET location service in a communication system is disclosed. The method comprises a first SUPL enabled terminal (SET) of the communication system sending a first Secure User Plane Location (SUPL) message to a home SUPL Location Platform (H-SLP) of the communication system for starting a session to query a plurality of location information of a second SET of the communication system, the H-SLP performing a positioning procedure with the second SET according to the first SUPL message, the second SET providing the plurality of location information, and the H-SLP sending a plurality of second SUPL messages to the first SET.