This paper proposes a wide-band and wide-angle scanning Ku/Ka dual-band phased-array antenna. The dual-band antenna array consists of Ka-band PCB-based slot antenna elements and Ku-band metallic banyan tree antenna elements. The operating bandwidth of both bands is extended to 4GHz, and the beam scanning coverage achieves ±60° and ±30° for Ku and Ka bands, respectively. By special treatment of the PCB, the channel isolation between Ku and Ka elements is better than -30dB and -18dB in two bands, which can support the simultaneous working situation of both antennas. Besides, the feeding structures of both antennas are flexible to be utilized in a phased-array system. A prototype of Ku/Ka antenna array is also fabricated. The measured active VSWR, channel isolation and scanning patterns are in good agreement with the simulated results, which demonstrates its good radiating performance and indicates the promising application in advanced phased array systems.