Abstract: The electron density profile inversion from vertical incidence ionograms, which is essential for research on the ionospheric structures and wave propagation, has received extensive attention. The model method is common for the inversion of vertical sounding ionogram. The inversion method of ionospheric profile was proposed by Carlo Scotto based on the Huang Xueqin's ionospheric vertical profile model. With this premise, we apply the Gauss model to F₁ layer for the improvement of Huang Xueqin's model. The inversion critical frequency of F₁ layer agrees with the measured value. Also we use the anti-Gauss model of the F₁ layer as the joint layer to ensure the continuity of the F₁ and F₂ layer section. The validity of the algorithm is also verified by simulation analysis.