A dump truck exhaust pressure reduction device comprises a pressure reducing box arranged on a longitudinal crossbeam at the bottom of a truck. A first end sealing plate and a second end sealing plate are arranged on the two axial end faces of the pressure reducing box respectively, one end of a connecting pipe is communicated with the pressure reducing box through a middle circular hole of the first end sealing plate, and a flange is arranged at the other end of the connecting pipe. One end of a gas outlet pipe is communicated with the pressure reducing box through a circular hole formed in the position, close to the second end sealing plate end, of the radial side of the pressure reducing box. The dump truck exhaust pressure reduction device can reduce dump truck exhaust emission pressure and change the exhaust emission direction, and therefore pollution influence on the environment is reduced, and the device is beneficial to the body health of constructors and on-site civilized construction.