Abstract: A multi-protocol determining method based on a CAN bus is provided, which includes a mode setting step and two or more modes are set in a controller of the CAN bus. The multi-protocol determining method based on the CAN bus includes a listening step, and the modes are taken turns to read a packet from the communicated node. The multi-protocol determining method based on the CAN bus further includes a confirming step. In the confirming step, if the packet is received successfully by one of the modes, the CAN bus is set to work in the corresponding mode. The controller sends one or more requesting packets, each having a communicating request based on a predetermined protocol, to the communicated node, and if the controller receives a feedback packet from the communicated node successfully, the protocol of the communicated node is identified to be the predetermined protocol.