Excavation beneath the existing high-rise building would lead to the loss of pile bearing capacity. The pile ultimate base resistance loss due to the additional stress caused by excavation was obtained based on the calculation formula for rock-socketed piles by using Mindlin’s stress solution and a simplified method, respectively. The results of theoretical analysis were compared with that of finite element analysis. The relationship between the ultimate base resistance loss ratio and excavation width and depth was analyzed. Parametric studies were conducted to analyze the influencing factors of the loss ratio. Results show that the loss ratio increases with the increase of excavation width and it shows an initial faster increase followed with a slower increase until a constant value. The loss ratio was approximately linear function of excavation depth. The better the quality of the rock mass, the smaller the loss ratio, which is more obvious for higher unconfined compressive strength of the intact rock. With the increasing of embedded depth, the loss ratio decreases gradually to stable values, which is more obvious for better quality rock mass.