Abstract: Inclined pile foundation is one of common foundations, such as bridge abutment or wharf, while there are few studies on negative skin friction for inclined piles. The negative skin friction of single inclined pile and inclined pile groups in viscous soil layer consolidated under surface load is studied by model tests. The variation of the negative skin friction of pile, tip resistance of pile and the settlement of each soil layer with consolidated time are measured. For comparison, the single vertical pile and vertical pile groups are tested under the same conditions. It is shown that the dragload caused by the negative skin friction of pile is significantly influenced by time effect and pile group effect for both vertical pile and inclined pile; the negative skin friction of pile will reach 80 %～90 % of the maximum negative skin friction under test conditions when pile-soil relative displacements reach 2 mm.