Abstract: In order to find out the effects of different coatings on the reduction of negative skin friction, the cohesive soil with a plastic limit of 18% as the test soil is studied based on the large shear tests. The influences of the moisture content and different coatings on the negative skin friction are emphatically studied. The results show that when the moisture content of the cohesive soil is slightly larger than that of the plastic limit, the reduction effects of negative skin friction are better, and the reduction effects of paraffin oil mixture, polymer nanomaterial or paint on concrete surface are basically the same. When the moisture content of cohesive soil differs greatly from that of the plastic limit, using the paraffin oil mixture as the pile side concrete coating has the best effects on the reduction of negative skin friction. The position of neutral point can be determined by different methods, and the negative skin friction of piles can be reduced by different applicable conditions.