Abstract: Aiming at recognition of the arc sound signal in different welding status,the mechanism of arc sound generation and propagation were investigated to MIG butt welding with spray transfer.It is proposed that arc sound is an associated thing of gas discharge,is the result of transmitting by the wave when the plasma collectively vibrates,is also the outcome of their combined action,including the sound source and the sound track.Among them,the spectrum characteristic depends mainly on the frequency respond of sound track.Based on the above analysis,the linear generation model of arc sound was set up.The linear prediction coefficients(LPC)a_i,reflection coefficientsand logarithm area ratio coefficientswere extracted by Levinson-Durbin algorithm.In addition,the combined characteristic vector of arc sound signal was constructed.