A compatible circuit, comprising: a printed circuit board PCB, and one group of compatible devices which are in a Pin-to-Pin form and have different internal structures, wherein the compatible devices and the PCB are assembled together; the internal structures of the compatible devices are configured to be matched with a link compatibility selection requirement; and the compatible devices are configured to conduct a link selection output on at least two links which are inputted and need compatibility according to the link compatibility selection requirement, wherein there are N links which are inputted and need compatibility, and the N links are a first link to an N th link respectively; N is a natural number greater than or equal to 2; accordingly, one group of compatible devices comprises N compatible devices, which are a first compatible device to an N th compatible device respectively; there are M output ends, and M is a natural number greater than or equal to 2, wherein: the first compatible device is configured to connect at least one link of the inputted first link to the N th link to a first output end to output, and select the at least one link of the inputted first link to the N th link which is connected to the first output end to be under a working state when the first compatible device and the PCB are assembled together; the N th compatible device is configured to connect at least one link of the inputted first link to the N th link to at least one output end of the first output end to the M th output end to output, and select the at least one link of the inputted first link to the N th link which is connected with the at least one output end to be under a working state when the N th compatible device and the PCB are assembled together; and so on, until a compatibility selection of any connection between N inputs and M outputs are completed through the first compatible device to the N th compatible device. a printed circuit board PCB, and one group of compatible devices which are in a Pin-to-Pin form and have different internal structures, wherein the compatible devices and the PCB are assembled together; the internal structures of the compatible devices are configured to be matched with a link compatibility selection requirement; and the compatible devices are configured to conduct a link selection output on at least two links which are inputted and need compatibility according to the link compatibility selection requirement, wherein there are N links which are inputted and need compatibility, and the N links are a first link to an N th link respectively; N is a natural number greater than or equal to 2; accordingly, one group of compatible devices comprises N compatible devices, which are a first compatible device to an N th compatible device respectively; there are M output ends, and M is a natural number greater than or equal to 2, wherein: the first compatible device is configured to connect at least one link of the inputted first link to the N th link to a first output end to output, and select the at least one link of the inputted first link to the N th link which is connected to the first output end to be under a working state when the first compatible device and the PCB are assembled together; the N th compatible device is configured to connect at least one link of the inputted first link to the N th link to at least one output end of the first output end to the M th output end to output, and select the at least one link of the inputted first link to the N th link which is connected with the at least one output end to be under a working state when the N th compatible device and the PCB are assembled together; and so on, until a compatibility selection of any connection between N inputs and M outputs are completed through the first compatible device to the N th compatible device. the first compatible device is configured to connect at least one link of the inputted first link to the N th link to a first output end to output, and select the at least one link of the inputted first link to the N th link which is connected to the first output end to be under a working state when the first compatible device and the PCB are assembled together; the N th compatible device is configured to connect at least one link of the inputted first link to the N th link to at least one output end of the first output end to the M th output end to output, and select the at least one link of the inputted first link to the N th link which is connected with the at least one output end to be under a working state when the N th compatible device and the PCB are assembled together; and so on, until a compatibility selection of any connection between N inputs and M outputs are completed through the first compatible device to the N th compatible device.