Abstract: The plate penetration test proposed by Tan and his team is introduced to measure the undrained shear strength of dredged clay with high initial water contents. A series of plate penetration tests are performed on three kinds of dredged clay distributed in different areas in China. The effect of loading rate on undrained shear strength and the change law in penetration depth with penetration time are investigated as a supplementary work of the plate penetration test method. In addition, the undrained strength behavior of dredged clay and its main influential factors are investigated. The normalized behavior of undrained shear strength based on plate penetration tests is compared with that based on vane shear and fall-cone tests to verify the effectiveness of plate penetration tests applied on dredged clays with high initial water contents.