Swirl-Loop Scavenging (SLS) improves the performance of 2-stroke aircraft diesel engine because the involved swirl may not only benefit the scavenging process, but also facilitate the fuel atomization and combustion. The arrangement of scavenge port angles greatly influences in-cylinder flow distribution and swirl intensity, as well as the performance of the SLS engine. How-ever, the mechanism of the effect and visualization experiment are rarely mentioned in the litera-ture. To further investigate the SLS, Particle Image Velocimetry (PIV) experiment and Computational Fluid Dynamics (CFD) simulation are adopted to obtain its swirl distribution char-acteristics, and the effect of port angles on scavenging performance is discussed based on engine fired cycle simulation. The results illustrate that Reynolds Stress Turbulence model is accurate enough for in-cylinder flow simulation. Tangential and axial velocity distribution of the flow, as well as the scavenging performance, are mainly determined by geometric scavenge port anglesαgeom andβgeom. For reinforcement of scavenging on cross-sections and meridian planes,αgeom value of 27° and βgeom value of 60° are preferred, under which the scavenging efficiency reaches as highas 73.7％. Excessive swirl intensity has a negative effect on SLS performance, which should be con-trolled to a proper extent.