A substrate integrated waveguide (SIW) radial sixteen-way power divider is presented. This power divider adopts two layer substrates, one of which is used to design the radial power divider cavity of the SIW, and the other layer is used to design the star-shaped microstrip isolation network. To improve the isolation performance, radial slots are cut in the metal layer of the SIW, and isolation resistors are added. The step impedance probes ensure good matching of input and output ports. For verification, a SIW radial sixteen-way power divider is manufactured and measured. The measured result shows that the 15-dB input bandwidth and output bandwidth of the SIW sixteen-way power divider reaches 12.6% and 20.2% respectively, the insert loss (IL) is lower than 2 dB, and the isolation between the output ports is better than 15 dB.