A multi-band antenna is disclosed and comprises a substrate and an electro-conductive layer. The electro-conductive layer comprises: a feed-in terminal; a ground terminal; a connecting portion extended forward from the feed-in terminal; a first high frequency portion extended leftward from the connecting portion for controlling a third frequency band; a low frequency portion bent and extended leftward from the connecting portion for controlling a first frequency band and a second frequency band; and a second high frequency portion extended rightward from the connecting portion for controlling a fourth frequency band. Furthermore, the second high frequency portion is connected with the ground terminal and wider than the first high frequency portion; and harmonic oscillations are generated between the second and first high frequency portions to control a fifth frequency band. Hence, the multi-band antenna of the present invention can meet the requirement of various communication standards.