Abstract: A probability-based imaging approach is employed to identify the damage in plate for Lamb wave structural health monitoring.In this study,an ellipse locus,indicating possible locations of the damage,is determined by the time-of-flight of damage-scattered Lamb wave signals and the spatial position of a transmitter-receiver pair in the sensor network.The inspection area is evenly meshed.The shortest distances between each mesh node in the inspection area and the ellipse locus are calculated.We map the distance to the probability of the damage occurrence,which leads to a grey image for each transmitter-receiver pair when the probabilities are quantified at all mesh nodes with a grey-scale. Individual grey images from all transmitter-receiver pairs of the sensor network are fused to accentuate the damage by employing the image fusion technique.The probability-based imaging approach is experimentally verified by evaluating through-thickness hole damage in an aluminium plate.It is suggested that the approach is an effective way for identifying the location and extent of damage,helping to promote the practical use of Lamb wave structural health monitoring.