Although the health data exchange standard of Health Level 7(HL7) V2.x (Version 2.0-2.5) has been widely used in hospital and has served well in these few years, the process that hospitals apply the standard of data transfer is very difficult. Because there is no explicit methodology in the HL7 V2.x development process, the gateway design is very complex. However, V3 strives to improve the V2 process and its outcomes. In this paper, the authors present an HL7 V3 gateway design based on the Web Services which can solve the problems of the HL7 V2.x. Web Services is an information exchange protocol regardless of the implementation platform, and is currently the main technology in enterprise application integration (EAI). We firstly introduce how to build HL7 V3 gateway with Web Services, then focus on the design of HL7 gateway, finally realize the parsing and transmission of HL7 V3 message.