The present invention provides a virtual machine system and a method for switching hardware devices thereof. In the virtual machine system, the hardware devices are classified into all-time sharing devices, time division switching devices and all-time exclusive devices based on using fashions. For the time division switching devices, the method for switching hardware devices is adopted, comprising steps of: upon system switching, sending a corresponding switching signal to a device model (DM) module corresponding to a foreground Guest OS and a DM module corresponding to a background Guest OS; the DM module corresponding to the foreground Guest OS releasing the hardware devices from its device space; the DM module corresponding to the background Guest OS adding the hardware devices released by the DM module corresponding to the foreground Guest OS to its device space. It is possible to implement switching of hardware devices among different Guest OSs by the system and method of the invention.