In this study, a series of laboratory experiments on the response of sand-clay seabed under progressive waves were carried out to investigate the process of sediment suspension over a liquefied seabed. The sand-clay beds with various clay content (CC) ranging from 0 to 15% were tested for a specific wave condition. The excess pore water pressure (EPP), suspended sediment concentration (SSC) and elevation of mixed beds were recorded for each test. The experimental results indicated that seabed with a certain amount CC was easier to liquefy compared with pure sandy bed. The SSC of liquefied sand-clay bed is bigger than that of non-liquefied mixed bed. The SSC above sand-clay bed is smaller than that of sandy bed, but the erosion depth of mixed bed is bigger than that of sandy bed.