The present inventive concept relates to a method for improving a lifespan of a liquid crystal display (LCD) of a masked stereolithography (MSLA) 3D printer, the method including the steps of: slicing a three-dimensional (3D) image into two-dimensional (2D) images; outputting the 2D images to the LCD; calculating irradiation area coordinates of UV LEDs in accordance with the 2D images; and irradiating UV light of the UV LEDs on an area matching with the 2D images in accordance with the calculated irradiation area coordinates of the UV LEDs.