A tri-band omnidirectional dual-polarized antenna that includes a dielectric resonator, a first substrate containing a first feeding circuit; and a second substrate containing a second feeding circuit. The first substrate and the second substrate are both planar, which form a sandwiching structure with the dielectric resonator. The first and second feeding circuits are adapted to provide dual polarizations to three frequency bands. The antenna can be used in the tri-band wireless communication systems to provide large signal coverage and stable wireless access for mobile terminals.