Based on the needs of the RF integrated laboratory in avionics system，one kind of broadband dual-polarized quadruple-ridged circular horn antenna was developed according to the transmission principle of conical horn antenna and the matching characteristics of broadband waveguide. Its working principle, performance and electrical structure were analyzed and designed.Through actual fabricating and testing of the antenna, excellent electric performance parameters were obtained. The measured results were basically consistent with the design. The antenna possessed more than 3 octave broadband matching characteristics in C,X,Ku band, also a very high cross-polarization isolation(B>22 dB) and a high gain(10 dB-20 dB). It is demonstrated that the proposed method is correct and effective.