A separator for a lithium-sulfur battery comprising: a porous substrate; and a coating layer present on at least one surface of the porous substrate, wherein the coating layer comprises a polymer represented by the following Chemical Formula 1: wherein R 1 to R 6 are the same as or different from each other, and are each independently selected from the group consisting of hydrogen; a substituted or unsubstituted C1-C20 alkyl group; (R 14 R 15) amino (C2-C10) alkyl group; a substituted or unsubstituted C3-C20 cycloalkyl group; a substituted or unsubstituted C6-C20 aryl group; and a substituted or unsubstituted C4-C20 heteroaryl group; or R 1 and R 2, R 3 and R 4 and R 5 and R 6, together with an amide bond or an imide bond including nitrogen, each independently form a 5 to 50-membered ring including a substituted or unsubstituted C6-C20 aryl group or a substituted or unsubstituted C4-C20 heteroaryl group; R 14 and R 15 are the same as or different from each other, and are each independently selected from the group consisting of hydrogen; a substituted or unsubstituted C1-C20 alkyl group; a substituted or unsubstituted C3-C20 cycloalkyl group; a substituted or unsubstituted C6-C20 aryl group; and a substituted or unsubstituted C4-C20 heteroaryl group; or R 14 and R 15 together with an amide bond or an imide bond including nitrogen, form a 5 to 50-membered ring including a substituted or unsubstituted C6-C20 aryl group or a substituted or unsubstituted C4-C20 heteroaryl group; R 1 and R 2, R 3 and R 4, R 5 and R 6 and R 14 and R 15 are optionally bonded to each other to form an aliphatic or aromatic ring including a heteroatom; at least one of R 1 to R 6 comprises an aromatic ring, or is connected to another substituent of adjacent R 1 to R 6 through an aromatic ring; R 7 to R 13 are the same as or different from each other, and are each independently selected from the group consisting of hydrogen, oxygen, and a substituted or unsubstituted C1-C10 alkyl group, and when R 7 to R 13 are oxygen, they form a double bond with the bonded carbon atom; m is each independently an integer of 0 to 5; and n is an integer from 5 to 5,000. a porous substrate; and a coating layer present on at least one surface of the porous substrate, wherein the coating layer comprises a polymer represented by the following Chemical Formula 1: wherein R 1 to R 6 are the same as or different from each other, and are each independently selected from the group consisting of hydrogen; a substituted or unsubstituted C1-C20 alkyl group; (R 14 R 15) amino (C2-C10) alkyl group; a substituted or unsubstituted C3-C20 cycloalkyl group; a substituted or unsubstituted C6-C20 aryl group; and a substituted or unsubstituted C4-C20 heteroaryl group; or R 1 and R 2, R 3 and R 4 and R 5 and R 6, together with an amide bond or an imide bond including nitrogen, each independently form a 5 to 50-membered ring including a substituted or unsubstituted C6-C20 aryl group or a substituted or unsubstituted C4-C20 heteroaryl group; R 14 and R 15 are the same as or different from each other, and are each independently selected from the group consisting of hydrogen; a substituted or unsubstituted C1-C20 alkyl group; a substituted or unsubstituted C3-C20 cycloalkyl group; a substituted or unsubstituted C6-C20 aryl group; and a substituted or unsubstituted C4-C20 heteroaryl group; or R 14 and R 15 together with an amide bond or an imide bond including nitrogen, form a 5 to 50-membered ring including a substituted or unsubstituted C6-C20 aryl group or a substituted or unsubstituted C4-C20 heteroaryl group; R 1 and R 2, R 3 and R 4, R 5 and R 6 and R 14 and R 15 are optionally bonded to each other to form an aliphatic or aromatic ring including a heteroatom; at least one of R 1 to R 6 comprises an aromatic ring, or is connected to another substituent of adjacent R 1 to R 6 through an aromatic ring; R 7 to R 13 are the same as or different from each other, and are each independently selected from the group consisting of hydrogen, oxygen, and a substituted or unsubstituted C1-C10 alkyl group, and when R 7 to R 13 are oxygen, they form a double bond with the bonded carbon atom; m is each independently an integer of 0 to 5; and n is an integer from 5 to 5,000.