The Location Service (LCS) feature which provides the terminal UE’s geographical location information has been important issues in IMT-2000 system. The existing location positioning methods are classified into the cell ID based, OTDOA, and network assisted GPS. In this paper, a new hybrid location positioning method which combine three of these methods is proposed. Then the LCS protocol is developed under SDL (Specification and Description Language) development environment after designing a new LCS system architecture and behavior. This protocol design covers the LCS functional model and signaling procedure, system architecture, primitive and data structure, and process SDL diagrams.