Virtualization is the key technology of cloud computing. Hypervisor provides an abstraction layer between the virtual machine and the host hardware, which allows the user to allocate memory for running the virtual machines over the available memory of a host. This technique is called memory overcommitment. In order to reduce the impact of this technology on the performance of the virtual machines, hypervisor must provide an efficient memory reclamation mechanism. In this paper, the author proposes a solution: using the nonvolatile memory as a cache device for hypervisor to exchange page file data. The author divides the space from the system memory to simulate the nonvolatile memory devices, and modifies the algorithm in the KVM module, and sets five kinds of testing environments. The experiments show that compared with the existing Ballooning technology and Hypervisor swapping technology, using the nonvolatile memory and with low priority queue algorithm, the virtual machine performance can be improved by 30% and 50%.