The invention discloses a W wave band microfilter antenna based on rectangular coaxial line structures. The antenna is nested into a filter as harmonic oscillators of the filter; the harmonic oscillators comprise a first harmonic oscillator, a second harmonic oscillator and a third harmonic oscillator; the first harmonic oscillator and the second harmonic oscillator are arranged at the input end of the filter; the third harmonic oscillator is arranged inside the carinal cavity of the filter as a carinal cavity type antenna; the first harmonic oscillator, the second harmonic oscillator and thethird harmonic oscillator are connected through rectangular coaxial lines for realizing coupling; and the length of the rectangular coaxial line between the first harmonic oscillator and the second harmonic oscillator is quarter wavelength. The antenna has the advantages of light weight, small coupling between lines, large operation bandwidth, small chromatic dispersion and the like.