A quad-ridge dual-polarized broadband horn cone antenna for millimeter wave 5G applications has been designed and simulated. The composition of the quad-ridge dual-polarized horn antenna can be viewed as two symmetrical dual-ridge horn antennas, using a new coaxial line with a new feed technology that gradually thins from the transition of the quad-ridge waveguide to enhance the tunability of the physical performance. The antenna working frequency is 18–50 GHz, the VSWR in the working band of this antenna is less than 2:1, the isolation is less than -35dB, the gain typical value is 15 dBi, the cross-polarization isolation is more than 35dB, the radiation map keeps good characteristics in the whole frequency band.