A method for merging graphic layers is provided. The method includes: receiving a plurality of graphic layers in a current frame; assigning sequence numbers to the graphic layers according to an overlay order; judging whether a first graphic layer and a second graphic layer vary in a period; merging the first graphic layer with the second graphic layer when judging that the first graphic layer and the second graphic layer do not vary in the period; and displaying the graphic layers in order of the sequence numbers according to the sequence numbers, wherein the first graphic layer and the second graphic layer are adjacent graphic layers.