激光等离子体中包含了反映激光焊接过程特征的信息。利用激光等离子体光电信号同步检测系统，检测激光等离子体的光电信号并进行光电信号的对比分析，阐明了电信号与等离子体温度之间的关系；对A304不锈钢、430不锈钢、碳钢Q235等材料的激光表面自熔焊接过程的等离子体电信号进行了实时检测及概率密度分布分析，对深熔焊特征最明显的A304不锈钢进行了电信号概率密度分布的标准差分析。研究结果表明：利用激光等离子体电信号能够实时反映激光焊接等离子体的温度变化的特点，可以根据激光等离子体电信号概率密度分布来分析激光焊接模式的特点，进一步的标准差分析法可以判断A304不锈钢激光焊接的模式。

A lot of information reflecting laser welding process are involved in laser-induced plasma. The electrical signal and spectral signal from laser-induced plasma are detected by a synchronous electrical and spectral information acquisition system and the signals are compared. And then the relationship between electrical signal and plasma temperature is illustrated. The electrical signals of the induced-plasma for stainless steel A304、stainless steel 430 and carbon steel Q235 in laser surface auto genous welding are detected in real-time and analyzed by the probability density distribution. The analysis of the standard deviation of probability density distribution of the electrical signal from the strainless steel A304 laser welding with the most obvious deep penetration characteristics is presented. The results indicate that the temperature variation of laser induced-plasma can be real-timely detected by the electrical signal, and laser welding mode can be identifed by the probability density analysis of the electrical signal of the laser induced-plasma and the laser welding mode of stainless steel A304 can be determined by the standard deviation analysis.