Abstract: Laser neutralization of high-energy negative hydrogen ion beams has been experimentally demonstrated as a novel technique capable of achieving extremely high neutralization efficiency. However, research in this field remains challenging due to the high cost of experimental facilities and the lack of effective theoretical simulation methods. To address this, a two-dimensional fully kinetic model was developed to simulate the photo-neutralization process of high-energy ion beams. This model integrates the Particle-in-Cell (PIC) method with the Monte Carlo Collision (MCC) approach and incorporates a dedicated photon-neutralization reaction module. It self-consistently solves the Poisson equation and the equations of particle motion, while coupling photon-induced reactions with neutral-particle collisions. This framework captures the spatiotemporal evolution of beam ions, electrons, and neutral atoms within the laser cavity. The simulation results were preliminarily validated against experimental data and were further employed to systematically investigate the effects of laser intensity, wavelength, and beam energy on neutralization efficiency and beam morphology. The results indicate that neutralization efficiency increases linearly with photon density; shorter-wavelength lasers achieve higher efficiency under equal power conditions; and higher beam energy reduces neutralization efficiency by shortening the ion residence time within the finite-length photon field. This study provides an effective theoretical framework for investigating the photo-neutralization mechanism of negative hydrogen ion beams, elucidates the coupling between space-charge effects and beam collimation, and establishes a theoretical foundation for optimizing and designing photo-neutralizers in high-power neutral beam injection systems.