The invention discloses a four-wheel-drive pesticide mist spray vehicle which is characterized by comprising a front frame (1), a rear frame (2), a transmission system, two pairs of travel mechanisms (12), a steering system and a mist spray system. The front frame (1) is hinged to the rear frame (2) by a steering seat. The four-wheel-drive pesticide mist spray vehicle has the advantages that the four-wheel-drive pesticide mist spray vehicle is driven by four wheels, is good in integral rigidity, high in strength and climbing capacity and stable in operation and has small turning radiuses; the distances among the wheels can be conveniently adjusted by the aid of the travel mechanisms, so that the four-wheel-drive pesticide mist spray vehicle is applicable to field parcels with different seedling distances; the four-wheel-drive pesticide mist spray vehicle is provided with gear boxes, and accordingly the height of chassis can be increased; the hydraulic power-assisted steering system of the four-wheel-drive pesticide mist spray vehicle is simple in structure as compared with the traditional hydraulic power-assisted steering system positioned at a front wheel, and accordingly the weight of the integral four-wheel-drive pesticide mist spray vehicle can be reduced; various components of the integral four-wheel-drive pesticide mist spray vehicle are in close fit with one another, and accordingly the four-wheel-drive pesticide mist spray vehicle which is a pesticide spraying vehicle is applicable to various operation environments of paddy fields, dry farmlands and the like.