Electronic health record (EHR) as a means of medical informatization has stored and accumulated big data of medical processes and results. Knowledge graph as a means to extract structured knowledge from massive data has recently shown broad application prospects in many industries. The application of knowledge graph technology to the analysis of EHR data can help obtain valuable medical knowledge and experience which could be used to improve the effectiveness and efficiency of medical industry significantly. This paper firstly introduced the development status of EHR

the existing famous EHR data sets and their application results. Secondly

on the basis of summarizing the current developments of knowledge graph

it analyzed the trend and hot-spot migration of knowledge graph in medical field as well. Then

it summarized the research and application progresses of EHR based medical knowledge graph which include the information extraction

data integration

query expansion

clinical diagnostic support and disease prediction of EHR

etc. Finally

this paper also gave the future development directions and challenges of EHR based medical knowledge graph.