Considering the spacetime characteristics of the GaAs photocathode image intensifier in ns-level gated imaging， this study undertakes a theoretical simulation and experimental validation. For theoretical simulation， the radial RLC transmission model of the photocathode is enhanced by incorporating transmission line impedance. This refinement enables a more accurate description of the optical shutter's behavior during the gating process. Experimental evidence confirms that removing the anti-ion feedback film enhances the optical shutter， aligning it closely with the electric shutter. Specifically， when the driving electric pulse width is 17.7 ns， the difference between the optical shutter width and the electric shutter width is merely 1.1 ns. For experimental validation， a spatial dispersion model of photoelectrons， driven by a segmented linear shutter pulse voltage after the first close attachment， is established using the Monte Carlo simulation method. Simulation outcomes indicate that the spatial resolution degradation of the GaAs photocathode in gating imaging is inferior to that of the S20 photocathode. At a spatial resolution of 20-line pairs per millimeter （lp/mm）， GaAs maintains 80% of its static spatial resolution， whereas the corresponding figure for the S20 photocathode is less than 70%. Notably， the theoretical simulation aligns seamlessly with the experimental results， affirming the applicability of the model for analyzing and optimizing image intensifier structural parameters. This model serves as a foundational framework for enhancing gating imaging performance.