A multi-band antenna includes a grounding element, a first antenna working on a wireless wide area network, a second antenna working on a wireless local area network, and a third antenna operating on a wireless local area network. The first antenna includes a first conductive piece, a first radiating element extending from the first conductive arm, a coupling radiating element and a feeding line. The second antenna includes a second conductive piece, a first resonant element extending from the second conductive piece, a second resonant element and a feeding line. The third antenna includes a third conductive element, a first conductive arm extending from the third conductive element and a second conductive arm and a feeding line. The first conductive piece is connected to the second conductive piece.