Abstract: As a novel, safe and high efficient spectrum utilization technology, orbital angular momentum(OAM) has attracted a great deal of attention in scientific community. In this paper, a broadband and multimode OAM antenna which works in X-band is designed based on uniform circular array(UCA). The antenna is composed of rotatingly arranged triangular element uniform antenna array. Its characteristic is that the number of positive and negative modes is related to the feed mode and the rotation mode of the array elements in the uniform circular array. Simulation experiments show that the antenna works at X band (9.33-10.37 GHz) and bandwidth is 1.04 GHz, relative bandwidth is 52%, and the modes of this antenna is more than the rectangular patch antenna with same number of elements. The antenna has the advantages of simple feeding network, wide bandwidth and easy control of the number of modes.