A black matrix, a preparation method therefor, and a system thereof, a display substrate, and a display device are provided. The preparation method includes: forming a black matrix thin film on a substrate; on one side, away from the substrate, of the black matrix thin film, carrying out first exposure processing on the black matrix thin film; on one side, close to the substrate, of the black matrix thin film, carrying out second exposure processing on the black matrix thin film; and developing the black matrix thin film after the first exposure processing and the second exposure processing to form the black matrix.