Based on the feature of vertical crack of pile caps and settlement of angled pile in a piled wharf, we think the reason lies in that the angled piles in the piled wharf do not enter into favorable bearing stratum and the oblique piles are acted by negative frictional resistance. It is proposed that the thixotropy of soft ground during pile driving and the river deposition can also exert the negative friction resistance to the pile. The coefficient value of negative friction resistance is compared between the silty ground and sandy soil.