Abstract: The present invention provides a method, system and apparatus for transmitting information across signaling networks. The method includes: when a signaling transfer point belongs to more than one signaling network at the same time, setting a mapping relation between different signaling networks on the signaling transfer point; signaling networks to which the signaling transfer point belongs include a first signaling network and a second signaling network; the signaling transfer point, after receiving a message indicating a destination signaling point code sent by first signaling network and when judging that there is no signaling point where the signaling point code is the destination signaling point code in the first signaling network, converts the message into a message in the second signaling network according to the mapping relation; and when judging that the destination signaling point of the converted message is available in the second signaling network, forwards the message.