A novel cavity backed slot antenna based on multi-layer substrate integrated waveguide is designed and manufactured by utilizing the resonant cavity to form symmetrical field excitation, and its radiation characteristic is studied and simulated. The proposed antenna using double -layer SIW to realize its feeding circuit and cavity structure has the advantage of low profile, light weight and convenient integration. The promoting effect of ring-slot structure on the radiation performance is considered. Finally, the test structure with a bandwidth of -10 dB return loss at 150 MHz is manufactured. And the maximum gain is 8 dB, and the maximum cross-polarized radiation is -12 dB. The good agreement between the measured results and the simulated results demonstrates that the design method is effective.