A backlight keyboard includes a first language keyswitch set having adjacent first and second keyswitches, a first backlight module disposed under the first language keyswitch set, and a masking sheet. The masking sheet is suitable for the backlight keyboard and a second backlight keyboard including a second backlight module and a second language keyswitch set. The first and second keyswitches on the backlight keyboard coincide with a third keyswitch in the second language keyswitch set on the second backlight keyboard. The masking sheet has a first light-exit region layout corresponding to the first, second, and third keyswitches for allowing light to be incident to symbols on the first, second, and third keyswitches. In other words, the masking sheet of the present invention can be applied to different backlight keyboards having different language keyswitch sets.