To study the influence of heeling angles on the lubrication flow field characteristics and the variation law of the churning power loss of ship,based on the Moving Particle Semi-implicit method，the lubrication flow field characteristics of marine reducer of eight kinds of conditions were analyzed.The results show that,under same input shaft speeds,initial lubricating oil volume and heeling angles,the lubrication performance of the marine reducer is better in the moving forward condition than in the backward condition.The high-speed splashed oil in moving forward condition is mainly located in the meshing zone between the output gear and the transmission gears,while the high-speed splashed oil in the backward condition is mainly located at the intersection of the splashed surface and the circumferential surface of the output gear.By analyzing the variation of the number of particles on the initial liquid surface under different working conditions,it is found that the number of particles splashed in the gearbox is the largest and the lubrication effect is the best when the heeling angle is 30°.The oil churning power loss of the gear increases with the increase of the heave angle.At the same heeling angle,the fluctuation range of the oil churning power loss in the moving forward and in the backward conditions of the marine reducer tends to converge,and their mean values are roughly the same.