A combined instrument vehicle for a transformer substation grounding device site test comprises a vehicle body. The combined instrument vehicle is characterized in that a grounding electrode slot, a current wire coil slot, a voltage wire coil slot, a hammer slot, a universal meter slot, a distance measurement meter slot and a clip-on ammeter slot are formed in a fence plate type packing case of the vehicle body, the fence plate type packing case is arranged on the upper portion of the vehicle body, the position, perpendicular to the side face, in the middle of the lower portion of the vehicle body is provided with an axle, the two ends of the axle are provided with wheels, an upward handle is arranged upwards on the rear side face of the vehicle body, and two supporting legs are arranged downwards on the rear side face of the vehicle body. The combined instrument vehicle for the transformer substation grounding device site test is novel and suitable in combination, convenient to use and particularly applicable to site use of transformer substation grounding device grounding resistor test operation and storage of measurement tools, and the measurement tools commonly used for transformer substation grounding device grounding resistor site test operation are contained in the combined instrument vehicle.