Choose the appropriate welding procedure parameters is the key to improve the welding quality and production efficiency. In the case of CO,2, gas protection welding process,control variable method is used to test the impact of a single welding parameter on the impact performance of welding joints. The welding wire with mechanical properties and chemical composition that meet the requ-irements of the classification society is selected. The vertical and upward butt welding position which has a significant impact on the impact performance of the welded joint is adopted. The welding parameters such as temperature,gas flow,welding current,number of welding layers and number of welding passes are separately adjusted for testing. The impact tests are carried out on the welding seams,and the test data and results are analyzed to obtain an effective method to improve the impact performance of the welding seams. The influences of different parameters on the welding performance are also explored,providing experimental reference and theoretical basis for relevant engineers to select welding parameters with ideal impact performance in production.