Access control mechanisms are vital to the privacy preservation and information security in electronic medical record system. In this paper, we analyze the existing drawbacks in traditional access control models firstly and outline the characteristics of next generation access control UCON. Then we apply the idea of UCON to electronic medical record system to meet the challenge of confidentiality, privacy preservation and data integrity. Then the novel access control formalisms of electronic medical record are presented. Various applications are presented to demonstrate its effectiveness.