The Lamb wave based damage monitoring techniqe was one of the research focuses in structural health monitoring (SHM). In the light of the problem of signal difference caused by sensor performance deviation in PZT array and Lamb wave based damage monitoring, the actuation, propagation and sensing processes of the Lamb wave were analysed. According to the characteristic that the propagation chanels with the same distances have the same direct wave transfer functions,a new PZT sensor electromechanical coupling coefficient compensation method was proposed for consistency compensation of the structural response signals. The experimental validation indicated that the new method could suppress the signal deviation caused by the difference of the performance of the piezoelectric sensor to a certain and improve the acurrcy of the monitoring results.