Display panel, preparation method thereof, and display device

A preparation method of a display panel includes: forming multiple compensation groups on a substrate to obtain an array substrate, where the multiple compensation groups include at least first compensation group and second compensation group, and brightness difference of light-emitting elements of same light-emitting color in the first compensation group and the second compensation group under a same gray scale is larger than a preset value; calculating thicknesses of first color film layer, second color film layer and third color film layer corresponding to each of the multiple compensation groups respectively; forming the first color film layer, the second color film layer and the third color film layer on light-emitting side of the first light-emitting element, the second light-emitting element, and the third light-emitting element respectively according to the thicknesses of the first color film layer, the second color film layer and the third color film layer obtained by calculation.