The invention discloses an air conditioner and a display controlling method thereof. According to the display controlling method of the air conditioner, the lightening time of a fine line display area is controlled to be longer than that of a thick line display area in one cycle period. By prolonging the lightening time of the fine line display area, the brightness of the fine line display area is improved, and the brightness of the thick line display area is consistent with that of the fine line display area, so that the uniformity of the whole display brightness of a display screen during displaying is improved and the user experience is improved.