The embodiment of the invention provides a terminal, a terminal peripheral component, a signal transmission system and a signal sending and receiving method, wherein the terminal comprises a first audio module and a USB socket; the first audio module is connected with a universal serial bus USB socket in the terminal through an inter-IC audio I2S bus channel and is used for sending a to-be-sent signal to the USB socket; and the USB socket is used for providing a physical connection interface between the terminal and the terminal peripheral component.