The invention discloses a silicon-based small-sized common-caliber dual-frequency dual-polarized broadband array antenna. The antenna comprises a plurality of dual-frequency dual-polarized antenna units, and each dual-frequency dual-polarized antenna unit adopts a laminated structure and consists of a low-frequency band radiation unit, a high-frequency band radiation unit, two frequency band feedstructures and a metal grounding plate. The low-frequency-band radiation unit is provided with a square hole and is placed in the high-frequency-band radiation unit to achieve the common caliber. Thehigh-resistance silicon is adopted as a dielectric substrate, so that the array element size is greatly reduced, and the miniaturization requirement is met. The bandwidth of the antenna is broadened in a manner of hollowing out a silicon-based air introduction layer. The common-caliber dual-frequency dual-polarization broadband array antenna can work in two frequency bands with the frequency ratiobeing about 2 at the same time, the characteristics of the two frequency bands are dual polarization, the antenna array layout is reasonable, and the common-caliber dual-frequency dual-polarization broadband array antenna has the advantages of being simple in structure, small in size, good in polarization performance, high in antenna isolation and the like.