Abstract: Based on the load tests on eight field piles at four sites of Jianghai West Road in Wuxi City, the bearing and deformation characteristics of piles, bearing capacities at pile tip and friction behaviors of the grouted piles are studied by comparing the field test results of the ungrouted and grouted piles. The results show that the pile tip grouting technique can significantly improve the bearing capacity of pile foundation and has a good effect on improving the stability of pile quality. The cement-stabilized soil is formed at the pile tip by the pile tip pressurized grout, which the sediment at the pile tip is effectively improved, and the bearing performances of the pile tip and the bearing stiffness are significantly enhanced. Moreover, the side friction ultimate resistance is significantly improved by the pile tip post grouting, and the side friction ultimate resistance of the grouted piles is larger than that of the ungrouted ones. Consequently, the stability of the bearing capacity of the pile foundation is improved by the pile tip post grouting.