In order to solve the problem of dual-or multi-mode composite guidance detection under the limited diameter ,based on the basic principle of interferometer direction-finding, a design method of direction-finding antenna system with high precision and non-fuzzy non-uniform circular array interferometer was presented.The element antennas are set up based on the idea of stagger baseline ambiguity resolution in this method. The method was proved to be reasonable, effective and feasible by means of mathematical analysis and simulation results.