A method for identifying memories of virtual machines is provided. The method is adapted to a computer system executing at least one virtual machine, and an operating system is executed on the virtual machine. The method includes the following steps. A kernel file of the operating system is obtained, and the kernel file includes version information of the operation system. A source code and a configuration file of the operating system are obtained according to the version information, and the versions of the source code and the configuration file are complied with the version of the operating system. An object file is generated by compiling a fixed interface function with the source code according to the configuration file. Memory pages of the virtual machine are identified according to the object file. Furthermore, a computer system using the foregoing method is also provided.