Abstract: In this paper, an 8×8 dual-polarized slot antenna array using substrate-integrated coaxial line (SICL) is proposed for millimeter-wave. Traditional millimeter-wave dual-polarized arrays require vertically stacked feeding network, leading to high profile and increased manufacturing costs. The proposed innovative feeding network exploits the dual-mode composite characteristics of the SICL. The dual-polarized radiation of the array has been excited by designing a transition structure which transfers the coaxial mode to the cavity mode and a dual-mode power-dividing network. This design achieves the integration of the dual-polarized feeding network within a single layer while maintaining high isolation, effectively reducing the profile. The simulation results show that the proposed antenna array can achieve an overlapped bandwidth of 24.1 GHz~27.8 GHz, a high-isolation level over 30 dB and a good dual-polarized radiation performance. With the advantage of simple feeding structure, low profile and low manufacturing costs, the proposed array has the potential of wide application in dual-polarized high-gain millimeter-wave communication.