The invention provides a combined motor vehicle for highway and bridge marked line clearing. The combined motor vehicle comprises a flat plate transportation vehicle and a driving type water clearingvehicle positioned at the front side of the flat plate transportation vehicle, wherein a
clean water box, a hydraulic
system, a first engine, a diesel tank, a power generator, a storage battery, a water feeding pump, a high-pressure water pump and a
vacuum pump are arranged on the flat plate transportation vehicle; a water inlet of the high-pressure water pump is connected with the bottom of the
clean water box through a high-pressure water inlet
pipe; an air extraction opening of the
vacuum pump is connected with a water outlet of the high-pressure water pump connected with the upper part ofthe front side of a
slag and water collecting and discharging device through a
vacuum pumping pipe and is connected with a water inlet of a high-pressure water clearing
disc assembly through a high-pressure water outlet
pipe; a
slag and water inlet of the
slag and water collecting and discharging device is connected with a slag suction water opening of the high-pressure water clearing
disc assembly through a fixed slag suction pipe. The combined motor vehicle has the advantages that the clearing effect is very good; waste water and residue slag can be recovered; the construction effect and theconstruction effect can be effectively improved. The high-pressure water clearing
automation degree is improved; the work intensity of workers is reduced, so that the popularization and the application of the high-pressure water in aspects of
automation and industrialization can be promoted.