Abstract: With the rapid development of the Internet, information leakage occurred frequently. Today, network security isolation and information exchange technology has become a research focus in information security. Analyzing the advantages and disadvantages of the existing isolation techniques, this paper proposed a mechanism for security isolation and information exchange, which overcomes unreliability issue in one-way communication with the potential covert channels under controlled. It coordinates the contradiction between security isolation and information exchange among different security level networks. In addition, the mechanism also has advantages, such as security isolation in physical level, reliable communication and good expansibility. It is well suited for multi-level security isolation and information exchange occasions.