Taking the muddy sediment nearshore of Zhoushan city in Zhejiang Province for example，a flume experiment by regular waves is carried out on the incipient motion for the muddy sediment.The results indicate that muddy sediment has three states of incipient motions,i.e.,slight suspension of thin layer,individual exfoliation of surface layer,as well as roll up and suspension of the mud.The threshold wave height decreases with the increase of the wave period under the same water depth.Taking the state of roll up and suspension of the mud as the criteria for the incipient motion of muddy sediment，experimental values of the threshold wave height are close to the calculated values by the formula of Misaki Sato and Dou Guoren,thus the average of the calculated results by the two formulae can be used for estimating the threshold wave height of muddy sediment.With the state of roll up and suspension of the mud as the criteria for the incipient motion of muddy sediment，the maximum of the processing sediment concentration is often between 0.8 and 2.0 kgm3,and the maximum of the processing sediment concentration shows an exponential increasing relation with the increase of the critical shear stress by waves.The results of this research can be used to explore the hydraulic characteristics of sediment in muddy coastal areas,and provide reference for the numerical simulation of coastal sediment and parameters selection for the engineering analysis.