The excitation of NRD guide is a key-problem to the planar/non-planar microwave hybrid integrated circuit. An efficient excitation method of the LSE 01mode in NRD guide through transverse slot was rigorously analyzed by combining the vector Green’s functions with the moment method. This exciting structure has many advantages of simple structure, small size, high excitation efficiency and weak energy leakage. And it is of important practical significance in the design of hybrid integrated circuits.