This invention discloses a prepaying method of the LCS system. It has the prepaying service and the prepaying orientation service on the service control point belonging to the prepaying users. The method includes the following steps: the calling user refers the orientation message to the gateway mobile position center. The mentioned gateway mobile position center judges the address types of the calling user and the called user who receives the orientation message, to ascertain the user type. According to the user type, the gateway mobile position center the user belongs to sends the charging request to the service control point to finish the charging process and the sending out of the orientation information.