Abstract: A coplanar waveguide(CPW) differentially-fed frequency reconfigurable antenna is proposed.By designing a DC bias circuit to change the working states of the four PIN diodes, the differentially-fed frequency reconfigurable antenna can be reconfigured in two frequency bands, 2.02 to 2.89 GHz (35.4%) and 3.27 to 3.66 GHz (11.3%), and the performance of frequency reconfiguration barely has influence on the radiation patterns of the antenna, the average gain of the two states can achieve 3.18 dBi and 3.61 dBi, respectively. This antenna which combines the differential technology and frequency reconfigurable technology, has a compact CPW structure and uses wide bands, thus can be applied to the 2.45 GHz band of WLAN and two bands of WiMAX, 2.45 GHz and 3.50 GHz.