Highway subgrade pavement flatness detection device and detection method

The invention discloses a highway subgrade pavement flatness detection device and detection method.The highway subgrade pavement flatness detection device comprises a material box containing pigment, and the bottom end of the material box is provided with moving wheels which are symmetrically distributed through a supporting plate; discharging ports distributed in a linear array mode are formed in the bottom end of the material box in the length direction, baffles are installed at the discharging ports in a sealed and sliding mode, discharging square pipes corresponding to the discharging ports are installed at the bottom end of the material box, and transverse moving plates located in the discharging square pipes in a sealed and sliding mode are fixedly installed at the bottom ends of the baffles. The material box is provided with a first driving assembly for driving the baffle to move transversely, and the two sides of the material box are each fixedly provided with a fixing plate which is arranged in an in