Suppressing ion migration in perovskite solar cells is crucial for high photovoltaic efficiency and stability. Guanidinium (GA)-based materials enhance lattice stability by forming a hydrogen bonding network with perovskite crystals, which impedes the migration of iodine ions. However, there is insufficient evidence regarding the mechanisms by which GA+ ion doping suppresses ion migration. This study explores the impact of GA+ ion doping on suppression ion migration using surface photovoltage (SPV) spectrum and a photovoltaic phase vector model. Moderate GA+ ion doping enhances charge separation, thereby increasing the overall photovoltaic output. Light-chopping-frequency-modulated SPV measurements confirm rapid improvement in charge transfer. Furthermore, the SPV phase model indicates a decrease in the component related to ion migration, leading to a counterclockwise shift in the phase angle with increasing GA+ ion doping. This research contributes to our understanding of GA+ ion doping effects on perovskite performance, offering insights for advancing perovskite solar cell technology.