A dual-band antenna assembly is positioned on a substrate, and includes an insulation body, a plane antenna and a microstrip antenna. The insulation body includes a plane surface paralleled to the substrate, and a side surface perpendicularly extending from edges of the plane surface to the substrate. The plane antenna includes a first feed portion and a first radiator. The first feed portion passes through the substrate to the plane surface of the insulation body. The first radiator is substantially positioned on a center of the plane surface of the insulation body, and electrically connected to the first feed portion. The microstrip antenna includes a second feed portion and a second radiator. The second radiator is a microstrip, electrically connected to the second feed portion and positioned on the side surface of the insulation body.