An on-vehicle data transmission method, comprising: switching to transmitting on-vehicle data via a second communication network by an on-vehicle communication module (102, 40, 50), if it is determined by the on-vehicle communication module (102, 40, 50) that a first communication network is abnormal in a process of transmitting the on-vehicle data to an external data processing device via the first communication network; and converting the on-vehicle data to be transmitted into data in a preset format for transmission when the on-vehicle communication module (102, 40, 50) switches to transmitting the on-vehicle data via the second communication network, wherein the on-vehicle data is divided into different types of on-vehicle data to be transmitted according to a first standard, and for each of the different types of on-vehicle data to be transmitted, the data that is capable of expressing expected complete content is long data; and that the converting the on-vehicle data to be transmitted into data in the preset format is to convert the long data into corresponding one or more short messages comprising a message header and a message body, wherein the message header at least indicates a relationship between the short message where the message header is located and the long data, and the message body indicates the content represented by the short message, characterized in that the long data is converted into corresponding multiple short messages based on a PDU encoding format, and that the message body of each short message is capable of independently expressing sub-data having independent meaning in the long data. switching to transmitting on-vehicle data via a second communication network by an on-vehicle communication module (102, 40, 50), if it is determined by the on-vehicle communication module (102, 40, 50) that a first communication network is abnormal in a process of transmitting the on-vehicle data to an external data processing device via the first communication network; and converting the on-vehicle data to be transmitted into data in a preset format for transmission when the on-vehicle communication module (102, 40, 50) switches to transmitting the on-vehicle data via the second communication network, wherein the on-vehicle data is divided into different types of on-vehicle data to be transmitted according to a first standard, and for each of the different types of on-vehicle data to be transmitted, the data that is capable of expressing expected complete content is long data; and that the converting the on-vehicle data to be transmitted into data in the preset format is to convert the long data into corresponding one or more short messages comprising a message header and a message body, wherein the message header at least indicates a relationship between the short message where the message header is located and the long data, and the message body indicates the content represented by the short message, characterized in that the long data is converted into corresponding multiple short messages based on a PDU encoding format, and that the message body of each short message is capable of independently expressing sub-data having independent meaning in the long data.