The invention discloses a monopole-loop-based pattern-reconfigurable antenna comprising a dielectric substrate, a coplanar waveguide feed structure, and a metal unit etched on the dielectric substrate. A rectangular metal ring, a coplanar waveguide feeder line, and coplanar waveguide floors are etched on the front side of the substrate. First metal bars and second metal bars parallel to the first metal bars are etched on the back side of the substrate in a coupling mode; and switches are loaded on the first metal bars. The antenna pattern is can be reconfigured by controlling turning on or off of the switches. According to the invention, the antenna has advantages of small size, light weight, simple structure, wide impedance bandwidth, and simultaneous realization of E-surface and H-surface pattern reconfiguration and is suitable for fields of military and civil radars, wireless communication, and intelligent weapon guidance and the like.