Beipan River Bridge is located on the Beipan River Grand Canyon in the middle of Yunnan-Guizhou Plateau. The bridge pile, diameter of 2.8m, subjects to the vertical load design value of 58000KN, the thickness embedded in the breeze rock more than 85% of pile, was almost a full rock-socket pile, its bearing load was large and embedded in rock deeply. Based on test method of self-balancing, the bearing characteristics of large-diameter rock-socket pile in argillaceous area have been analyzed, including the axial force of pile, side friction, the tip resistance and so on. The results indicated that the bearing characteristics of the part in sock was as same as the friction piles in muddy dolostone area; From the results of test the side friction of pile could be estimated higher in strong weathering argillaceous dolomite area while the friction in weak or puny weathering muddy dolostone was relatively close to the value of exploration reports. Pile tip resistance had a greater potential. Finally, analyzed the measured curve, it could be seen that the calculation of bearing capacity was less than the test result, and the pile foundation was safety enough.