A satellite navigation automatic driving system of a high-speed seedling transplanter is composed of an RTK-GPS, an attitude instrument, odometers, a rotation angle sensor, an electronic control steering wheel, a GPS data forwarding electronic control unit (ECU), an attitude instrument data forwarding electronic control unit (ECU), an odometer electronic control unit (ECU), a steering wheel electronic control unit (ECU), an embedded navigation computer EGC and the like. A traditional manual steering wheel is replaced by the electronic control steering wheel; the RTK-GPS and the attitude instrument are arranged at the center of a cross-over support on a seedling disc support; the odometers are arranged on walking reducers of left and right wheels; the rotation angle sensor is arranged at a steering mechanism of the bottom of a main reducer; each electronic control unit (ECU) is arranged near the sensor; the EGC is mounted at one side of the seedling disc support; the EGC is connected with the ECUs through a serial communication network; the EGC includes a man-machine interface as well as pre-data processing, attitude estimation and driving control modules; in seedling transplanting, a target point method is adopted to realize tracking automatic driving; and in corner turning, a method in which attitudes are adjusted around a corner turning center is adopted to realize automatic driving. With the satellite navigation automatic driving system adopted, the seedling transplanter can be driven by a computer, and therefore, onboard operation personnel can be reduced to only one seedling supplementing worker.