Abstract: Virtualization is a key technology in the field of cloud computing. It redefines and divides information resources, solves the problems of information resources in scheduling, allocation, isolation and other aspects, and greatly improves the utilization of information resources. Different virtualization technologies have some differences in performance loss due to different implementation methods.This article introduced two virtualization technologiesKernel-basedVirtual Machine (KVM) and VMware in detail from two aspects of architecture and function, used several popular performance testing tools to test the performance of physical machine, KVM and VMware, including CPU, memory, disk and network.Through the comparison of test results, it is found that two kinds of virtual machine will have 10% performance loss when the HDD(Hard Disk Driver) is read randomly; VMware virtual machine will have 10% bandwidth loss when it is used as TCP (Transmission Control Protocol) client; KVM virtual machine will have 60% bandwidth loss when it is used as UDP (User Datagram Protocol) server; and 20% bandwidth loss when it is used as UDP client. Based on the test results, we can choose the appropriate virtualization technology according to different emphasisin practical application.