Abstract: Underwater welding technology has been widely applied in the building and repairing of underwater construction in recent years. In the underwater welding technologies, local dry welding method which adopts local dry chamber to prevent the effect of water on the welding process has some advantageous such as better joint quality and ease to realize automatic welding. However, in the process of local dry welding the highpressure compress air need to be injected into the local dry chamber in order to prevent the water flow into it. In this paper, a numerical simulation method is adopted to study the structure of the wind field in the local dry chamber firstly. Based on the simulation results, the structure of local dry chamber is optimized. And then the impacts of the wind field in the local chamber to the welding process and arc characteristics such as the arc temperatures, velocities and pressures are analyzed. The simulation results show that the lateral wind has a great influence on the welding arc column, and the declination of arc column displays a linear relationship with the increasing of lateral wind speed. Finally, a highspeed camera is used in the welding experiments to photograph the arc shape under different lateral wind. It is found that the experimental results are consistent with the simulation results.