Abstract: Starting with the research on fourdimensional dynamic visual field, this paper establishes a virtual visual field test system of forest fire engine, makes experiments of the drivers intuitional judgment during operating visual field equipment, and gets the attenuation value of forest fire engine drivers visual field under fourdimensional dynamic structure. The results showed that the visual field attenuation occurred with the dynamic structure; the reason for attenuation was that the influence of time and environment was neglected under threedimensional static test; there were design and manufacturing defects in existing forest fire engine visual field equipment; this research on attenuation under fourdimensional dynamic structure will be helpful to breakthrough design on the equipment of forest fire engine visual field.