The invention relates to a vehicle-mounted central controller which comprises a processor, a memory, an address latch, a bus interface circuit, an external input signal acquisition circuit, an output signal control circuit and an auxiliary circuit. A high-power electric appliance is directly driven by a power switching element instead of a relay, so as to realize a function of diagnosing the related electric appliance. A special diagnosis device can be replaced by a notebook computer which is configured with special diagnosis software. The functions, such as downloading on-line programming application software, setting vehicle parameters, on-line diagnosis, and the like, can be realized by utilizing a USB (universal serial bus) interface. A vehicle control system application platform is formed by the vehicle-mounted central controller, an external signal acquisition part, an external controlled part and a touch screen. An application program can be specifically developed for the second time according to different vehicles or requirements, so as to solve the existing problem of vehicle that different controllers are needed to be developed independently and different control software are needed to be configured when different vehicles are configured, thereby avoiding a large amount of labor and financial waste.