Disclosed in the disclosure are a method, system and apparatus for processing slice image for 3D printing, and a storage medium. The method includes: acquiring a slice image of a three-dimensional model, and a relationship between a grayscale compensation parameter and a size adjustment value; determining at least one size adjustment value according to the slice image; determining at least one grayscale compensation parameter according to the at least one size adjustment value and the relationship between the grayscale compensation parameter and the size adjustment value; and respectively performing grayscale processing on edge pixels of corresponding contours in the slice image according to the plurality of grayscale compensation parameters, where the processed slice image is used for 3D printing.