To the problems of insufficient separation efficiency and significant pressure drop in traditional dynamic-pressure oil-gas separators used in aeroengine lubrication systems, a structural optimization scheme was proposed. Based on computational fluid dynamics (CFD) methods, the multiphase model was employed to numerically simulate the gas-liquid two-phase flow characteristics inside a multi-row-hole dynamic-pressure oil-gas separator. The flow field distribution and separation performance within the separator were systematically analyzed. It is shown that the gas-liquid phase interface in the oil-gas separator is clear. A uniform isobaric surface is formed inside the separator, and the velocity field distribution is reasonable. It conforms to the coupling distribution characteristics of a Rankine vortex and circulation flow. It is shown that beneficial circulating flow is generated by increasing the number of holes in the conical section of the multi-row-hole dynamic-pressure oil-gas separator. A separation efficiency exceeding 90% is achieved, and internal flow resistance is reduced. The adaptability of this structure over a wide range of operating conditions is further verified by comparative analysis under multiple operating conditions. The oil-gas separation efficiency is increased with the rise of the oil-gas ratio. It is also increased with the increase of the inlet flow rate. However, the separation efficiency is decreased when the temperature is either too low or too high. The requirement for high-efficiency separation in the aero-engine oil sump is met by the multi-row-hole dynamic-pressure oil-gas separator.