The article introduced the survey results of the affected factors to the fluctuation of multipurpose forest fire fighting vehicle. Based on the actual operation process of the vehicle, we conducted to develop the fluctuation models of vehicle in space with kinetic force which was caused by bumpiness of forest ground, and simultaneously, it bear by a kinetic force due to the working system on the vehicle. From the established model, equation of Lagranger type II was used to develop a fluctuation equation of vehicle. Using Matlab and Simulink 7.7 software to simulate and study the affected factors to the fluctuation of the vehicle.