The invention relates to a single-engine multiple-transmission operation mode of a road pollutant removal vehicle. The single-engine multiple-transmission operation mode comprises an engine, a clutch,a gearbox, a multiple-transmission box, a chassis hydraulic walking operation mechanism and a top-mounted pure mechanical transmission operation mechanism. According to the layout mode, the size of ahydraulic oil tank can be reduced to 1 / 3-1 / 4 of the original hydraulic transmission, the heat dissipation power of a hydraulic system is greatly reduced, meanwhile multiple motors, multiple high-pressure oil pumps, multiple control valves and other components are omitted, and the space is saved; meanwhile, compared with the top-mounted hydraulic transmission, by the adoption of the top-mounted pure mechanical transmission operation, the layout is simple, the failure rate is low, the maintenance is easy, a high-power hydraulic oil heat dissipation system is omitted, and the whole vehicle costis reduced; meanwhile the hydraulic walking operation is realized, and the requirements of large-torque and ultra-low-speed operation are met; and the output power of an engine is matched through themultiple-transmission box, the ultra-low-speed hydraulic walking during operation can be met, and the mechanical force-taking requirement of a high-pressure water pump and a high-pressure fan can be met.