Provided are a three-dimensional display device and a control method thereof. The liquid crystal display panel (21) displays left-eye picture frames and right-eye picture frames alternately. The left-eye picture frame comprises left-eye picture subframes and black picture subframes alternately displayed by a first display area (211) and a second display area (212) of the liquid crystal display panel (21). The right-eye picture frame comprises right-eye picture subframes and black picture subframes alternately displayed by the first display area (211) and the second display area (212). The backlight module (22) comprises a first backlight (221) and a second backlight (222) that are turned on alternately, so that the first backlight (221) provides lighting for the first display area (211) when the first display area (211) displays the left-eye picture subframe and the right-eye picture subframe, whereas the second backlight (222) provides lighting for the second display area (212) when the second display area (212) displays the left-eye picture subframe and the right-eye picture subframe. In the above manners, the brightness evenness of a three-dimensional display device can be enhanced.