The virtualization technology is one of the key technologies of the cloud computing. Meanwhile, monitoring virtual machine is an important function on the virtualization platform. In order to obtain the internal information of the virtual machine better, a lightweight virtual machine kernel module detection method (KMDM) is designed and implemented on the virtualization environment of Xen. The KMDM resides in the host machine and uses the virtual machine introspection mechanism to obtain the kernel module information of the virtual machine. The experimental results show that the KMDM can detect the kernel module information of the guest virtual machine, and the detection results are accurate and reliable.