Abstract: Based on the results of model tests and analysis of the failure-modes of tension piles set into rock, the existing formulas for calculating the bearing capacity of tension piles are researched. An improved formula is put forward, and the relative parameters in the new formula are also proposed. Finally, the improved formula is validated by the results of the model tests and is used to predict the ultimate uplift bearing capacity of the in situ tension piles at the Second Luzhou Changjiang Bridge.