The invention provides a broadband monopole microstrip antenna, and mainly solves the problem that a conventional monopole antenna is narrow in frequency band and complex in three-dimensional structure. The broadband monopole microstrip antenna comprises a dielectric substrate (1), a feed line (2), a radiation patch (3), a high frequency joint (4) and an earth plate (5). The radiation patch (3) isin the shape of an ellipse of which the long axis is in the vertical direction, the front end of the radiation patch is provided with an impedance match adjusting section (6), the earth plate (5) iscomposed of two mutually-perpendicular rectangular metal plates (51, 52), arc-shaped gaps (7) and (8) are respectively carved in the central positions of opposite edges of the two rectangular zones, and the vertical projection of the radiation patch (3) on the bottom of the dielectric substrate is in front of the arc-shaped gap (8) and covers the arc-shaped gap (7). The broadband monopole microstrip antenna can cover S and C wave bands, the working frequency band ranges from 1.62 GHz to 8.28 GHz, and the broadband monopole microstrip antenna can be used as a microwave radiation and reception front-end antenna of a broadband wireless communication, detection or monitoring system.