The Abel inversion based on a spherical symmetry of the ionospheric electron density distribution is a traditional inversion method of ionospheric occultation. However, the real ionosphere is not strictly spherically symmetric, which can cause error in inversion process of ionospheric occultation data. In this paper, we develop a non-spherically symmetric ionospheric occultation inversion method, in which the gradient information about international reference ionosphere three-dimensional ionospheric model is used to correct total electron content (TEC), thus the ionospheric electron density can be reconstructed from the corrected TEC by the spherical symmetric Abel inversion method. The inversion results retrieved from the measurements data of Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) ionospheric occultation are compared with the ionosonde data, showing that the result obtained from the new method is well coincident with the ionospheric electron density profile.