Abstract: The electrically controlled variable elements are mostly used in traditional frequency reconfigurable antennas to con-struct the feed network, which result in complex design and processing. In addition, the use of electronic components reduces the radiation efficiency and makes the performance unstable. In this paper, a mechanically tuned frequency reconfigurable antenna with high-order mode impedance matching is proposed. In order to use a fixed feed network for impedance matching without adding any electrically controlled variable elements, the antenna works in the third-order mode in two lower frequency bands to increase the in-put impedance. The proposed design increases the stability of the performance, improves the radiation efficiency, reduces the com-plexity of antenna design and processing, and reduces the cost. The antenna has achieved good resonance in the three 5G applica-tion bands of 2. 6 GHz, 3. 5 GHz and 4. 9 GHz, and the radiation efficiency has basically reached 90%.