A method for transmitting information across networks, characterized by comprising: 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 according to an interaction requirement of said different signaling networks; wherein the more than one signaling network to which the signaling transfer point belongs comprise a first signaling network and a second signaling network, and the mapping relation comprises a corresponding relation of network appearances of the first signaling network and the second signaling network and a corresponding relation of signaling point codes of the first signaling network and the second signaling network, and after receiving a message indicating a destination signaling point code sent by the first signaling network, and when judging that in the first signaling network there is no signaling point whose signaling point code is the destination signaling point code, the signaling transfer point converting the message into a message in the second signaling network according to the mapping relation, wherein the step of converting the message into the message in the second signaling network according to the mapping relation comprises: converting the destination signaling point code indicated by the message sent by the first signaling network into the destination signaling point code in the second signaling network according to the mapping relation; and forwarding the message in the second signaling network when in the second signaling network there is a signaling point whose signaling point code is the destination signaling point code and the signaling point is available in the second signaling network, which means that a state of the signaling point is office direction available. 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 according to an interaction requirement of said different signaling networks; wherein the more than one signaling network to which the signaling transfer point belongs comprise a first signaling network and a second signaling network, and the mapping relation comprises a corresponding relation of network appearances of the first signaling network and the second signaling network and a corresponding relation of signaling point codes of the first signaling network and the second signaling network, and after receiving a message indicating a destination signaling point code sent by the first signaling network, and when judging that in the first signaling network there is no signaling point whose signaling point code is the destination signaling point code, the signaling transfer point converting the message into a message in the second signaling network according to the mapping relation, wherein the step of converting the message into the message in the second signaling network according to the mapping relation comprises: converting the destination signaling point code indicated by the message sent by the first signaling network into the destination signaling point code in the second signaling network according to the mapping relation; and forwarding the message in the second signaling network when in the second signaling network there is a signaling point whose signaling point code is the destination signaling point code and the signaling point is available in the second signaling network, which means that a state of the signaling point is office direction available.