The piston ring pack is one of the crucial moving parts of two-stroke marine diesel engines because it has essential functions such as lubrication, sealing, and heat conduction. An oil injection lubrication mode for the ring pack through an independent oil-feed system is remarkable for two-stroke marine diesel engines. This study established a lubrication model for the ring pack. The model coupled ring dynamics, ring mixed/boundary lubrication, inter-ring gas dynamics, and asperity contact, especially considering this specific lubrication mode. The influence of lubricating oil-feed parameters (preliminary oil film thickness, oil-feed amount, oil-feed width, oil-feed position, and oil-feed ratio) on the lubrication characteristics of the ring pack was evaluated by the minimum oil film thickness and friction loss power. Finally, the orthogonal analysis method was used to optimize the lubrication characteristics.