A CAN bus data transmission method adopts the methods of dynamically changing frame priority, frame sequential control, a multiframe response mechanism, a multiframe selection strategy and the like to improve the reliability of CAN bus big data transmission; the priority of the first frame and the last frame of multiframe data is higher than common data, so the two frames can not be affected by the common multiframe data, and the normal receiving of important control information such as frame identity, frame length, frame check code and the like is ensured. For the multiframe response mechanism, frame head response and frame end response are added, so the effective receiving of the frame head, and the same time the condition that the frame head is error but continuously sends data is avoided, thus effectively saving the bus brad width, and improving the transmission efficiency; the frame end response contains error frame number, which makes the data transmitting terminal get the error frame number as quick as possible, so only the error frame number is re-sent, and the all the frame numbers are not needed to re-send to waste the bus band width. The invention greatly improves the reliability of receiving and sending of the CAN bus big data block, has a certain error detection and correction function, widens the application level of the CAN bus, and improves the robustness of the network system.