The utility model relates to a mark adjusting display device of an air conditioner. A group of rear projection type indicating light marking word film display device and a group of window type condensation irradiation marking word film display device with an illuminating light are combined to form the utility model. The illuminating light is arranged between the lower part of a masking frame at the edge of a transparent face mask and a marking word film. The light of the illuminating light is blocked and reflected in a directional mode by the masking frame. The marking word film is uniformly illuminated. The utility model can not lead eyes of a user to be directly projected. When the user is in a room and in a place with insufficient light at night, the user can clearly see various function marking words, can accurately carry out the temperature, the time and the air type of an air conditioner, and can accurately select and adjust the time and the program.