In order to solve the deficiency of the current three-way power dividers/combiners, a novel Ku-band three-way power divider/combiner in rectangular waveguide was presented, which was composed of a branch waveguide directional coupler, a coplanar magic T, two novel 90° waveguide bends and a waveguide matched load. Based on the power divider/combiner, a Ku-band three-way power dividing/combining network was established. The structure was modeled and optimized using three-dimensional electromagnetic simulation software HFSS. The sample was fabricated and measured. The measured results show that the transmission loss of the network is less than 0.12 dB, the return loss is better than 17 dB between 13.75 GHz and 14.5 GHz. After calculation, the power combination efficiency is greater than 98.6%. The performance of the Ku-band three-way power dividing/combining network is excellent.