A pixel-by-pixel calibration method is provided. Multiple sample cabinets are selected from to-be-calibrated cabinets to form a small screen with the sample cabinets, image acquisitions are performed on the small screen and luminance-chrominance mean deviation ratios are calculated. The sample cabinets are placed at fulcrum positions of a large screen to be calibrated, and the other remaining cabinets are placed at other positions. Full-screen original luminance-chrominance values are obtained by image acquisition on the large screen, original luminance-chrominance values of the sample cabinets are adjusted by the luminance-chrominance mean deviation ratios, and luminance-chrominance distribution fitting surfaces are generated by adjusted full-screen original luminance-chrominance values to amend the full-screen original luminance-chrominance values. Amended full-screen luminance-chrominance values are used as luminance-chrominance initial values and luminance-chrominance target values are set, and full-screen pixel-by-pixel calibration coefficients of the large screen are obtained. The effect of arbitrarily splicing LED cabinets after calibration can be achieved.