Method for displaying user interface of head-mounted display device

A method for displaying a user interface of a head-mounted display device, comprising:

• providing a graphic user interface which comprises a main interface region, an auxiliary interface region and a running program interface region, wherein the main interface region comprises one or more main interface icons, each of which corresponds to an application program;
• displaying at least a portion of the main and auxiliary interface regions on a display screen of the head-mounted display device, such that from an observation of a user wearing the head-mounted display device, said at least a portion of the main and auxiliary interface regions is displayed at a first distance from the user;
• receiving an application program running instruction;
• and
• displaying, in response to the application program running instruction, the running program interface region on the display screen of the head-mounted display device, such that from the observation of the user, the running program interface region is displayed at a second distance from the user, wherein the first distance is determined by:
• detecting, by an image sensor of the head-mounted display device, an external environment of the user, to determine whether a physical plane in the external environment that occupies more than a threshold display size or proportion of the head-mounted display device exists in the external environment;
• and
• using a distance between the physical plane and the user as the first distance if the physical plane does exist, such that from the observation of the user wearing the head-mounted display device, said at least a portion of the graphic user interface is displayed on the physical plane.