A Substrate Integrated Waveguide(SIW) is proposed, which bears the advantages of small size, easy processing, high Q value, and low cost, compared with the traditional slot antenna. The radiation characteristics of the proposed antenna can be optimized by adjusting the slot length, slot width, and cavity size. Calculating the model through electromagnetic simulation software HFSS, then the optimal structure of the antenna can be confirmed finally. The simulation results show that the relative bandwidth of this antenna is about 4.5%, the directivity is excellent, the resonance depth at the center frequency point is <-31 dB, and the maximum antenna gain is 5 dBi, which meets the design requirements and verifies the correctness of the design. The proposed SIW waveguide cavity-backed slot antenna broadens the available frequency spectrum of digital communication, which can provide new ideas for future research.