The disclosed folding mechanism comprises a rear frame member of a bicycle, which has a combining structure positioned at a front portion thereof, wherein the combining structure includes a first joining surface; a front frame member of the bicycle, which has a second joining surface positioned at a rear portion thereof for being joined with the first joining surface; at least one pivot structure, which is provided at an edge of the combining structure for connecting the front frame member, such that the front and rear frame members can relatively move on the pivot structure; and at least one binder, which is deposited at the combining structure of the rear frame member and a position on the front frame member adjacent to the combining structure for fixing the second joining surface of the front frame member and the first joining surface of the rear frame member at a combining position where the two joining surfaces contact mutually. By using the folding mechanism, a bicycle equipped with the same can be folded or expanded.