Abstract: Based on the old channel ground of a power plant improved by PHC pipe piles,the mechanical characteristics of PHC pipe piles are studied.The beating number and soil plug of PHC pipe piles during driving are tested,and the characteristics of driving PHC pipe piles are generalized.Using the optic fiber sensors and in-situ tests such as plate load tests,the distribution characteristics of pile stress are analyzed.The frictional resistance of PHC pipe piles relates with both soil properties and pile depth.The frictional resistance at the upper section of the pile is the smallest,the participation degree at the middle section is the maximal,and the axial stress at the lower section decreases at the fastest rate.On the basis of test data,the modified formula for the bearing capacity of PHC pipe piles is provided.It is proved to be reasonable by the plate load tests.