An exemplary dual-band antenna includes a first antenna unit and a second antenna unit for receiving /sending radio frequency signals corresponding generating a low resonant frequency and a high resonant frequency. The first antenna unit is perpendicularly connected to the second antenna unit. The second antenna unit includes a feed portion, two slots, two gaps and two grounding sheets. The feed portion is electrically connected to the first antenna unit and is used to receive radio frequency signals. The slots are adjacent to one side of the first antenna unit and are defined at the both sides of the feed portion, and the slots are connected with the feed portion and used to radiate radio frequency signals. The gaps extend away from a position of the first antenna unit and are defined at the both sides of the feed portion, and each gap communicates with corresponding slot. The grounding sheets are symmetrically positioned at both sides of the feed portion.