Abstract: The topology optimization method avoids the parameters scanning of the structure and directly optimizes the material arrangement, and is used in the design of passive microwave devices, which can greatly expand the design solution domain. In this paper, the singular radiation pattern microstrip antenna based on topology optimization method is studied. Firstly, the adjoint sensitivity with singular radiation patterns is analyzed, secondly, a two-dimensional metal optimization model based on transitional boundary conditions is constructed, and a variety of objective field functions for singular radiation are proposed again, such as high-gain beam directional deflection, equal-amplitude double-beams and arbitrary-direction linear polarizations. In order to verify the validity and accuracy of the algorithm, a microstrip antenna with a high-gain beam directional deflection pattern is fabricated and tested, and the test results are in good agreement with the topology optimization results. This method is particularly suitable for passive electromagnetic device design with complex targets.