The invention discloses an online automatic detection method for a hardware channel of a special vehicle control system. The special vehicle control system comprises a controller having a DO port, a DI port, an AI port and an AO port; and the DO port is a switch amount output channel port, the DI port is a switch amount input channel port, the AI port is an analog amount input channel port, and the AO port is an analog amount output channel port. The online automatic detection method includes a switch amount output channel detection step, a switch amount input channel detection step and an analog amount input and output channel detection step. The invention can effectively detect the normality of the hardware channel of the special vehicle control system, has the outstanding advantages ofsimple operation, high efficiency and fast detection speed, can improve the automatic testability of the hardware channel of the vehicle control system, and effectively reduces the skill requirementson the troubleshooting personnel; and the troubleshooting personnel can operate according to the instructions without having to be very familiar with the system hardware.