An in-situ geotechnical test in flume is carried out to study the strength rule of the formation of the silty fine sand hard shell on the surface of the bottom mud in Weifang Port area,clarifying the change of shear strength and penetration strength of soil under different wave conditions and velocity conditions,searching for the internal relationship between the plate state and wave current state of silty soil,and analyzing the influential factors of the formation of iron plate sand.The results show that the greater the sudden change of wave history progress,the more the strength of seafloor soil increases;the bigger the wave height,the more the strength of seafloor soil increases;the longer the wave current action time,the more the strength of seafloor soil increases.