A combination structure of a cart and a bicycle comprises a bicycle formed mainly by a backbone, a handle, a front wheel and a rear wheel; the handle, the front wheel and the rear wheel being combined to respective positions of the bicycle; a cart formed by a backbone, at least one front wheel, at least one rear wheels and at least one pushing rod; the cart being extended with at least one pushing rod; wherein a user can hold the pushing rods to rotate the at least one front wheel and the rear wheel so as to drive the cart to move forwards; and a hook extending from the cart for hooking the handle of the bicycle. The a cart may be combined to a bicycle directly or indirectly so that enabled old people or child, or expensive goods can be transferred easily.