Compatible design method and circuit

The embodiments of the invention relate to the technical field of electronics and disclose a compatible design method and circuit. The method comprises the following steps: detecting whether ID pin voltage corresponding to an identity identification number ID of a data line inserted into a terminal is a preset voltage threshold, wherein the data line comprises an OTG line, a three-segment type earphone cord, a four-segment type earphone cord and a MICRO_USB_5PIN type earphone cord; if it is detected that the ID pin voltage is the preset voltage threshold, according to an input selection trigger instruction, selecting to trigger and start the three-segment type earphone cord or the OTG line to work; and if it is detected that the ID pin voltage is not the preset voltage threshold, determining to trigger and start the four-segment type earphone cord or the MICRO_USB_5PIN type earphone cord to work. According to the embodiments of the invention, compatibility among an OTG function, a three-segment type earphone