Abstract: The index structures of HR+-tree,SEST spatio-temporal index and snapshot-increment index are blended,and a new spatio-temporal access method is proposed,which distinguishes the shared pointer and non-shared pointer.This method is named as EHR-tree,and is possible to not only process time slice and interval query,but also queries about events.The EHR-tree implementation uses a HR-tree structure for storing snapshots and a log data structure for storing increments and events that occur between consecutive snapshots.