Abstract: Magnetic confinement fusion energy is anticipated to become the ultimate clean energy source for human society due to its abundant fuel resources, safety, and environmental friendliness. Achieving fusion ignition requires plasma to reach extremely high energy confinement levels. Under normal circumstances, ohmic heating alone cannot achieve the high-confinement mode, necessitating additional auxiliary heating to transition from low-confinement mode to H-mode, which forms an edge transport barrier that significantly increases energy confinement time and overall plasma performance. As one of the most critical auxiliary heating methods in Tokamak, the penetration depth of neutral beam injection in plasma and its deposition power in the core are influenced by the edge pedestal density in H-mode. Precise control of pedestal density is urgently required for maintaining plasma stability during operation of future international thermonuclear experimental reactors. The research tool utilized in this paper is the OMFIT integrated modeling platform, currently recognized as one of the most mature integrated simulation platforms internationally for steady-state plasma modeling. It integrates the EFIT program for calculating equilibrium configurations, the ONETWO program for computing currents and source terms, the TGYRO program for simulating core kinetic profile evolution, and the EPED program for predicting pedestal structures in H-mode plasma. This study employed the OMFIT integrated modeling platform to investigate the modulation effects of neutral beam heating power (2-4 MW) on H-mode confinement performance in China’s HL-3 Tokamak, utilizing its magnetic configuration under fixed pedestal density conditions with 1 MA plasma current and 2.2 T toroidal magnetic field. Simulations demonstrate that increasing power from 2 MW to 4 MW reduces energy confinement time by 37.5% (0.32 s→0.20 s) while marginally elevating total thermal energy (W_E) from 0.57 MJ to 0.67 MJ, with ion thermal energy (W_E,i) dominating the increase (0.25 MJ→0.39 MJ, +56%) versus constrained electron thermal energy growth (W_E,e: 0.32 MJ→0.36 MJ, +11%). Turbulence transport analysis reveals that under 4 MW heating power, the growth rates of electron-temperature-gradient-driven instability modes increased dramatically at normalized minor radii ρ=0.5 and ρ=0.8, with trapped electron mode turbulence emerging at ρ=0.5. This leads to enhanced turbulent transport in the electron channel and substantially elevated electron thermal transport coefficients, causing electron thermal energy to approach saturation. Consequently, the ratio of total thermal energy to heating power decreases, ultimately resulting in reduced plasma energy confinement time. These simulation findings provide valuable insights for the design of operational scenarios in future fusion reactors.