As one of important and effective means for modifying the ionosphere, releases of neutral gases including H2O, CO2, H2, SF6, etc. can produce artificial ionospheric holes. In this paper, the ionospheric disturbances produced under various release conditions, including use of different release species (H2O and SF6), different release altitudes, and different amounts of released substance, are investigated based on an improved three-dimensional chemical release dynamics model which includes neutral gas diffusion, chemical reaction and the ambipolar diffusion of the plasma. The effects of release altitudes and release amount on ionospheric disturbances, morphology and the dynamics of ionospheric hole are studied. Furthermore, the results are also briefly discussed.