3D input device, head-mounted device and 3D input method

The invention provides a 3D input device. The 3D input device comprises a virtual button board providing module, a visual feature capturing module, a button selecting module, a confirming module and a displaying module, wherein the virtual button board providing module is used for providing a virtual button board and position information of the virtual button board; the visual feature capturing module is used for capturing visual feature information of a user and providing a visual cursor and position information of the virtual cursor according to the visual feature information; the button selecting module is used for providing a button selecting result according to the relation of positions of the virtual cursor and the virtual button board; the confirming module is used for confirming the button selecting result in response to a confirming operation of the user; the displaying module is used for displaying characters corresponding to the button selecting result. The invention further discloses a head-mounted device and a 3D input method. The 3D input device can be used for inputting the characters into a stereo display device.