Abstract: For a class of popular IP network applications,a prototype of performance-optimized communication network for virtual machines is proposed.A few virtual machines run on the top of Xen,which is high-performance virtual machine monitor and multiplexes the underlying physical host.Xen creates and manages these virtual machines.A new virtual network card is the core of the prototype.All virtual machines are interconnected by this card into a network.Compared with default model of Xen,the prototype can improve the communication performance and reduce the response time for request by 42%.