This article introduces a low-cost and high-efficiency W-band 4×4 substrate integrated waveguide(SIW) slot array antenna. The antenna consists a two-layer structure: the top radiation layer uses wide edge longitudinal offset slots standing wave array, which could realize high radiation efficiency; the bottom feeder layer adopts substrate integrated waveguide central rotate slots for feeding, which could decrease the transmission loss and realize difficulty of traditional power divider networks. Simulation software Ansys Electronic is used for optimizing the antenna array. The antenna sample is fabricated using the standard printed circuit board process. The test results are in good agreement with the simulation results. The maximum gain of the antenna array at 94 GHz is 16.8 dB, reflection coefficient is -30.1 dB, -10 dB bandwidth is 92.6-96 GHz, sidelobe level is 19.5 dB,the aperture efficiency of antenna array is 83%.