The invention discloses a coaxial waveguide filtering antenna with adjustable frequency. The coaxial waveguide filtering antenna comprises a standard WR-90 waveguide, wherein a waveguide excitation port and an antenna radiation port are formed in the two ends of the standard WR-90 waveguide respectively, a first tuning screw, a second tuning screw, a third tuning screw and a fourth tuning screw which are arranged in a row in the direction from one end to the other end of the standard WR-90 waveguide are vertically inserted into the upper surface of the standard WR-90 waveguide, the insertion depths of the first tuning screw and the fourth tuning screw are the same, the insertion depths of the second tuning screw and the third tuning screw are the same, a fifth tuning screw, a sixth tuning screw and a seventh tuning screw which are on the same straight line with the first tuning screw, the second tuning screw, the third tuning screw and the fourth tuning screw are vertically inserted into the lower surface of the standard WR-90 waveguide, the fifth tuning screw is located between the first tuning screw and the second tuning screw, the sixth tuning screw is located between the second tuning screw and the third tuning screw, the seventh tuning screw is located between the third tuning screw and the fourth tuning screw, and the insertion depths of the fifth tuning screw and the seventh tuning screw are the same. The center frequency of the antenna can be adjusted by adjusting the insertion depths of the screws, and the coaxial waveguide filtering antenna has the advantages of being simple and reliable in structure, convenient to process, low in loss, high in performance and the like.