Abstract: To solve problem that it is not easy to account both broadband and miniaturization in the design of traditional substrate integrated waveguide (SIW) power divider, a power divider based on slow-wave substrate integrated waveguide (SW-SIW) is proposed in this paper. The slow-wave structure units composed of microstrip lines are loaded on the metal surface of SIW instead of the continuous metal surface of traditional SIW. Compared with SIW of the same size, the cut-off frequency of SW-SIW is decreased by 40%, which can reduce the lateral size of the substrate integrated waveguide. When SW-SIW and SIW have the same phase shift, the longitudinal dimension of SW-SIW is smaller than SIW. The proposed power divider based on SW-SIW is achieved a size reduction with a wide bandwidth. The measurements show that the power divider has a bandwidth of 43.2% from 8.25 GHz to 12.8 GHz with the reflection coefficient |S₁₁| less than −10 dB. The phase consistency is good, and the miniaturization effect is obvious, so the proposed power divider is suitable for the application of compact microwave radio frequency front-end.