Abstract: This paper proposes a filtering crossover based on circular microstrip patch resonator. The orthogonality of the degenerate mode TM11A and TM11B in the circular microstrip patch resonator is used to realize the cross transmission of signals. At the same time, the coupling slots and coupling bridges are introduced between the two circular microstrip patch resonators, the signal can be efficiently transmitted from one circular microstrip patch filter unit to another, i. e. , cascade the two circular microstrip patch resonators, so as to realize the filtering function of the filtering crossover. In this design, the isolation between different transmission channels is achieved by using mode characteristics and rationally arranging input and output ports. In order to verify the design method, a planar filtering crossover with a 3 dB relative bandwidth of 9. 3% working at 2. 9 GHz is designed, manufactured and tested. Measured results coincide well with simulated ones, verifying the proposed design concept.