In order to deeply reveal the force transmission and damage mechanism of column-to-drilled-shaft connections， detailed finite element simulation of exist experimental test was conducted， and force transmission and damage mechanism were analyzed. After verification of finite element models， the effect of shear-span ratio， embedment depth， connection diameter-to-column diameter ratio and pile transverse reinforcement ratio on seismic performance of column-to-drilled-shaft connections was studied by numerical simulation. Results indicate that proposed finite element models can adequately replicate the mechanical behavior of column-to-drilled-shaft connection. The damage of connection region is presented as pile stirrup yielding induced by horizontal compression from embedment pier segment. Additionally， the connection strength increases with the increasing of shear-span ratio， connection diameter-to-column diameter ratio， embedment depth and pile transverse reinforcement ratio.