The seismic vulnerability analysis of gravity dam can predict the probability of dam damage at different levels under different seismic loads. It is significant to evaluate the seismic safety, optimize the seismic design and develop the reinforcement measures of gravity dam. Based on the uncertainty of the material parameters of concrete and the earthquake, the seismic vulnerability analysis of the Koyna gravity dam with the strain rate effect is carried out. The dam vulnerability analysis method and the seismic vulnerability curve of Koyna gravity dam are given. The results show when the strain rate effect is considered, the probability of severe damage and dam break is less than without considering strain rate effect. Dam head break, dam heel crack and combination failure are the typical seismic damages of gravity dam, which is in line with the actual damage of the Koyna dam.The results show that the dam head, dam heel and slope break are the key parts to focus.