A method of patterning a block copolymer layer, the method including: providing a substrate with a guide pattern formed on a surface thereof; forming a block copolymer layer on the substrate with the guide pattern, the block copolymer layer including a block copolymer; and directing self-assembly of the block copolymer on the substrate according to the guide pattern to form n/2 discrete domains, wherein the guide pattern includes a block copolymer patterning area having a 90-degree bending portion, and an outer apex and an inner apex of the 90-degree bending portion are each rounded, the outer apex having a first curvature radius r1and the inner apex having a second curvature radius r2, respectively, and the width of the patterning area W, the first curvature radius r1 and the second curvature radius r2, satisfy Inequation 1: 2 + 2 - ( 1 + 2 ) [ ( n + 2 ) 2 n  ( n + 1 ) ] 1 3 ≤ r 1 - r 2 W ≤ 2 + 2 - ( 1 + 2 ) [ ( n - 2 ) 2 n  ( n - 1 ) ] 1 3 . Inequation   1