An information processing adapter for an on-board diagnostic (OBD) includes an input connector inserted into a socket of the OBD, a circuit board connected to the input connector and a first output connector connected to the circuit board. The circuit board has a controller area network (CAN) transceiver and a microcontroller. The adapter gets vehicle driving information through the input connector and transmits to the microcontroller through the CAN transceiver to perform interpretation and format conversion, then sends the converted vehicle driving information to an external electronic device through the first output connector. With the format of vehicle driving information converted by the adapter, the information can be directly displayed or stored in various electronic devices without specific specification.