The present invention relates to a double frequency antenna, which comprises a feed part, a first radiation body, a second radiation body, a first grounding part, a second grounding part and a connecting part. The feed part is used to transmit the electromagnetic wave signal. The first radiation body is of an arc shape and electrically connected with the feed part. The second radiation body is annular and electrically connected with the feed part. The first grounding part is arranged on one side of the feed part and the second grounding part is arranged on the other side of the feed part. Theconnecting part is used to connect the first radiation body, the second radiation body and the feed part electrically. The present invention further provides a multi-input output antennal using the double frequency antenna. The double frequency antenna and the multi-input output antennal can simultaneously work in two frequency band of 2.4 GHz and 5.0 GHz central frequency, and the multi-input output antennal can effectively increase the isolation degree among various antenna units.