To investigate the behavior of laterally loaded corrosion damaged reinforced concrete (RC) pipe pile, the governing equation of chloride diffusion into RC pipe pile was established based on Fick’s second law. Considering initial and boundary conditions, the analytical solution of chloride diffusion equation was presented. The critical corrosion penetration of reinforcing steel corresponding to cracking of concrete cover occurs was presented based on thick-walled cylinder model. Based on Faraday’s law, the time for corrosion-induced cover cracking in RC pipe pile was estimated. Then the attenuation law of flexural stiffness of corrosion damaged RC pipe pile exposed to marine environments was investigated by introducing the reduction factor of flexural stiffness. The time-dependent behavior of laterally loaded corrosion damaged RC pipe piles exposed to marine environments was further analyzed. The analysis results show that the chloride-induced reinforcement corrosion had a significant effect on the behavior of laterally loaded RC pipe piles exposed to marine environments. The flexural stiffness of RC pipe pile decreased nonlinearly with the increase of exposure time. The maximum negative shear force and the lateral deflection increased with the increase of exposure time, while the bending moment decreased.