The present invention provides a duplex structure signal transfer point system for common channel signalling system No. 7, which includes a serial duplexed interconnection device; a duplexed network interface connected to the serial duplexed interconnection device, for performing an interconnection between signal message processing submodules; a parallel duplexed interconnection device connected to the duplexed network interface, for performing a parallel duplexed interconnection between unit level 2s and a duplexed unit level 3, wherein the duplexed unit level 3 is connected to the parallel duplexed interconnection device, for performing a protocol level 3 of a message transfer protocol in the common channel signalling system No. 7; and wherein the unit level 2s are connected to the parallel duplexed interconnection device, for performing a protocol level 2 of the message transfer protocol in the common channel signalling system No. 7.