The utility model provides a tractor front wheel driving electro- liquid automatic control device, structurally composed of a solenoid operated hydraulic valve and controlling transfer cases which are connected through an oil pipe. Compared with prior art, the tractor front wheel driving electro-liquid automatic control device of the utility model has the advantages of simple structure, practicality and unique design. Combining the technology of automatic combining of the brake case and the transfer cases, and the technology of automatic control of the front wheel driving electro-liquid, the utility model realize that the transfer cases combine automatically when the tractor brakes, with a speed one time higher than a tractor without said technologies and a braking distance reduced by fifty percent. The utility model greatly improves the running safety of the tractor, thus having big utility value.