从ＣＯ＿２激光焊接时等离子体产生的机理出发，针对厚板焊接，采用一套精密调节装置对辅助气体控制等离子体的主要工艺参数进行了试验研究，并对焊接时等离子体行为、小孔及熔池的运动进行观察。结果表明：无论采用何种常用气体，只要其压力稍高于金属蒸气压力，等离子体被压缩和控制，就可获得最佳的深穿透焊缝。 Starting from the plasma generation mechanism of CO_2 laser welding, a set of precision adjusting device was used to study the main process parameters of plasma assisted plasma gas control for plate welding. The plasma behavior, small holes and melting The movement of the pool was observed. The results show that no matter what gas is used, the best deep penetration weld can be obtained if the pressure is slightly higher than the metal vapor pressure and the plasma is compressed and controlled.