In this paper, over 40 pile load test data were reviewed and the bearing capacity of the piles was studied. Through the analysis of pile load tests, the bearing mechanism of pile is established as follows: (a) Skin friction is mobilized by pile shaft displacement and its magnitude depends on the order of shaft displacement. (b) Ultimate skin friction is observed at certain depth and this depth shifts downwards with increasing pile load. At above/below this certain depth, the magnitude of skin friction is smaller than the ultimate shear strength. (c) The magnitude of skin friction depends on pile length. When the pile length exceeds 30m, the skin friction is more than 95% of the bearing capacity of pile. From this bearing mechanism, the pile adhesion factor and neutral point of negative skin friction are evaluated.