Abstract: In clay shear deformation process, different shear rates have different effects on its structural damage, thus affecting its mechanical behavior. This paper takes the soft dredger fill from Tianjin Binhai New Area as research object. It discusses the structural about soft dredger fill, and carries out the triaxial shear tests to study effects on mechanical behavior caused by different shear rates, analyzes its mechanical effect of shearing rate. The test result indicates that as the shear rate increases, at low confining pressure condition, the strength and structural yield stress of soft dredger fill increase at first and then decrease, existing a critical shear rate. At high confining pressure condition, the strength and structural yield stress increase gradually, which shows a positive correlation with the shearing rate. The critical rate is disappearing gradually. However, at different confining pressure conditions, the cohesion of dredger fill decreases as the shearing rate increases. As the shearing rate increases, the internal friction angle shows an increasing trend at low confining pressure condition, which shows a decreasing trend at high confining pressure condition. In the shearing process, pore water pressure increases with the increase of axial strain to a certain value, and then becomes stable. With further increase of confining pressure, the stable value of pore water pressure shows a decreasing trend with the increase of shearing rate.