Abstract: Based on the virtual boundary integral equation method(wave superposition method),the spectral expression of the radiation sound pressure is derived by expanding the integral kernel function and unknown source density distributed with Fourier series on circumferential and meridian direction according to the geometry characteristic of the axisymetric cavity.Then,a new method for solving the 3-D acoustic radiation problem of the axisymetric cavity is presented by adopting the complex radius vector boundary technology.This method is called virtual boundary spectral method with complex radius vector.The present method can not only avoid the singular integral,but also overcome the non-uniqueness of solution effectively for all wave numbers.The comparisons with the analytical solutions and validation of numerical experiments show that the present method is accurate and efficient,which is suitable for a higher frequency range.