A lamp brightness remote controlling device is provided for regulating a brightness level of a lamp correspondingly provided with a wireless receiver unit, and includes a first central processor, to which an ambient brightness detector, a setting key, and a wireless transmitter module are electrically connected. The first central processor compares a user-set brightness level set by a user via the setting key with an ambient brightness detected by the ambient brightness detector, computes, and then outputs a comparison signal to the wireless transmitter module for transmitting to the wireless receiver unit on the lamp, so that a luminance of the lamp is automatically regulated to always keep a working environment at the user-set brightness level.