Abstract: A technology experiment on the welding repair of corrosion pits with Q235 (ϕ720×8.9 mm) pipe sample is carried out in Northeast Oil Pipeline Networks, which is made based on the technology requirements worked out including the max. allowable depth of weldable corrosion pits, min. distance between two patches and the distance of patch to the girth and spiral girth of pipe. Experimental results show that the fluid of low velocity and fluid pressure have slight impact on burn-through and hardness during welding repair, and burn-through at the position of vertical welding is more possible than that of other positions, therefore, during welding process, heat input needs to be controlled strictly.