Provided are an antenna, an antenna device, a terminal and a method for adjusting an operating frequency band of the antenna. The antenna comprises: a feed point, a feed branch and a coupling branch, wherein the feed branch is electrically connected to the feed point; and the coupling branch is coupled to the feed branch. The coupling branch comprises at least two grounding points, wherein one grounding point of the at least two grounding points is used for grounding, and other grounding points are optionally grounded or not grounded; alternatively, one grounding point of the at least two grounding points is grounded, and other grounding points are selectively grounded or not grounded. By means of the antenna provided in the embodiments of the present invention, grounding combinations of coupling branches are changed, so that operating frequency bands of the antenna are increased. Since different selected grounding combinations correspond to different operating frequency bands of the antenna, the headroom of the antenna only need satisfy the demand of the maximum headroom under various grounding combinations without meeting the requirements of headroom when the antenna operates all the time at the whole operating frequency band, so that it is not necessary to increase the headroom while covering the antenna at multiple frequencies.