The utility model relates to a frequency-reconfigurable microstrip antenna. The antenna is fed by adopting a side-feed mode and comprises a dielectric plate and an SMA connector, wherein the upper surface of the dielectric plate is provided with a semicircular radiating element, and an inner ring of the semicircular radiating element is vertically provided with a microstrip antenna; the lower surface of the dielectric plate is provided with a metal patch grounding plate; the metal patch grounding plate is transversely provided with a first slot and a second slot which are parallel to each other; the middle of a middle part of the first slot is provided with a patch radio frequency switch S9 in a crossed mode, the inner center of the SMA connector is connected with a microstrip feeder; and the outer surface of the SMA connector is connected with the metal patch grounding plate. According to the utility model, a filtering function is integrated in the frequency-reconfigurable microstrip antenna, so that the antenna is enabled to be used for sensing the whole frequency band, and then the bandwidth is adjusted so as to select an appropriate sub-band to carry out operations. The frequency-reconfigurable microstrip antenna can satisfy communication under various bandwidth and frequency band conditions, and has excellent application values in wireless communication.