Abstract: Using the two dimensional Howk-Brown criterion as the rock failure one, the horizontal normal stresses resulted from the variation of pile diameter under restriction of surrounding rock and the self weight of soil and rock penetrated by piles are considered based on the mechanism of shear-slip-dilation. A modified method for calculating the ultimate shaft resistance of rock-socketed piles is put forward based on the methods in the literature. The affecting aspects are analyzed, including the axial force, the rock strength modulus, the tension strength coefficient, the ratio of rock modulus to pile modulus, the pile diameter and the ratio of socket depth to pile diameter. The results indicate that the ultimate shaft resistance of rock-socket piles increases with the increase of the axial load, the rock strength modulus and the tension strength coefficient and the ratio of rock modulus to pile modulus. It decreases with the increase of the pile diameter and the socket ratio.