The recombination rate coefficients of molecular ion with electron are several orders greater than those of the dominant atomic oxygen ion in ionosphere F region,so the plasma densities in ionosphere can be greatly depleted by modest amounts of H₂ gas released at ionospheric altitudes.Based on a 2-D dynamics model including the neutral gas diffusion equation and the ion chemical reaction equation,this paper simulates the processes of H₂ released at ionospheric altitudes and analyzes the changes of ionospheric electron and foF₂(critical frequency of F₂ layer) at different temporal and spatial release conditions.Results show that:1)500 mol H₂ gas released at the ionospheric altitude diffuses swiftly,where the electron density decreases nearly 4% after 30 s and the foF₂(critical frequency of F₂ layer) decreases about 1%;2)When the same amount of H₂ is released at different altitudes,the maximum relative change rate of electron density will not appear when H₂ is released nearby the peak altitude of F₂ layer(hmF₂);3)The more amount of H₂ is released,the larger disturbance of electron density is caused,but there is not a linear relation between them;4)The disturbance amplitude of electron density in daytime is larger than that in nighttime when the same amount of H₂ released at hmF₂.