Aiming at the requirement of efficient excitation of whispering gallery mode(WGM) in optical microcavity, and based on the calculation results of mode electric field distribution by finite element software COMSOL, a simulation method for the excitation efficiency of WGM is designed. The method can be used to simulate the maximum depth of resonant peak of different modes under different coupling conditions of microcavity and tapered fiber, so as to determine the coupling condition of efficient excitation of the mode. On this basis, the excitation efficiency control of the mode and the excitation of high-order azimuth modes are simulated and analyzed. The simulation results show that by selecting a tapered fiber with a matching size and finely adjusting the coupling distance, the excitation control of the fundamental mode of the fabricated microrod cavity from under-coupling to over-coupling can be achieved. By adjusting the coupling position, the high-order azimuth modes can be excited with high efficiency.