An algorithm to improve the brightness uniformity of LED display screen is proposed based on display screen control technology and correction principle. The charge-coupled device (CCD) camera is used to collect the RGB images of display screen. The position of LED light is determined by using mathematical morphology and template matching method. The relative brightness of light emitting region is calculated according to grayscale value of light emitting region. The correction parameters of each light point are generated and pulse width modulation is used to control brightness of light points. Experimental results show that the proposed algorithm can effectively improve the brightness uniformity on LED display screen, and its display quality and prolong its service life.