Abstract: In order to improve the reliability of the pavement cleaning machine’s water tank and reduce the fatigue crack failure of the welded structure of the wave plate in the water tank under the impact of water flow, a structural optimization program of circular arc transition was used to reduce the degree of stress concentration, thereby increasing the service life of the wave shield. The influence of the transition arc position and radius on stress distribution was analyzed by finite element simulation. The simulation results showed that the stress concentration of the welded structure weakened the fatigue life of the wave shield, while the arc transition structure had a significant mitigation effect on the stress concentration, and its degree of relief was significantly related to the arc position and radius. As the distance between the arc and the weld bead decreased, or the radius of the arc increased, the stress concentration of the wave shield decreased, and the transition was more obvious from low-cycle fatigue to high-cycle fatigue.