The invention discloses a vehicle load detection method and a vehicle load detection device. The detection method comprises the steps of: S1) detecting an acceleration a of a vehicle; S2) calculating an acceleration resistance Fj of the vehicle; S3) calculating the mass m of the whole vehicle according to the acceleration a of the vehicle and the acceleration resistance Fj of the vehicle; and S4) calculating a vehicle load according to the mass m of the whole vehicle. The vehicle load detection method and vehicle load detection device provided by the invention can help a driver to detect the mass of the whole vehicle, the problem of overloading is prevented, the vehicle is effectively protected, the service lifetimes of the vehicle and parts are prolonged, and the maintenance cost is reduced; in addition, the vehicle load detection device provided by the invention is simple in structure, convenient to maintain and manufacture, and applicable to a lorry of any structure.