Abstract: In the array antenna design, the loss of the feed network directly affects its radiation efficiency, and the gap waveguide transmission line has the characteristics of low loss and easy processing, which is widely used in the design of millimeter-wave antenna. In this paper, a 16×16 slot array antenna operating in the W-band is designed based on the ridge gap waveguide (RGW), which adopts a uniform parallel feed. Firstly, the single layer feed network is analyzed, we find that due to the small spacing between adjacent RGW branches, it is difficult to achieve band-gap by using limited pin structures, resulting in increased coupling between branches and phase imbalance of feed output ports. In order to solve this problem, a two-layer compact power division network is designed, and the simulated array performance is in good agreement with the ideal uniform array. Furthermore, the center frequency of the area array is 93.65 GHz, the band range of -10 dB reflection coefficient is from 91.7 GHz to 95.6 GHz, the corresponding fractional bandwidth is 4.2%, the beam width of E plane and H plane is lower than 4°, and the radiation efficiency is higher than 75%, which verifies the effectiveness of the design.