In this work the gasoline compression ignition (GCI) combustion characterized by the premixed gasoline port injection and gasoline direct injection in a single-cylinder diesel engine was investigated experimentally and computationally. In the experiment, the premixed ratio, injection strategy, and exhaust gas recirculation (EGR) rates were varied with the pressure rise rates below10 bar/crank angle. The experimental results showed that the higher premixed ratio and earlier injection timing with high injection pressure resulted in advanced combustion phasing and improved thermal efficiency, while the pressure rise rates and NOx emissions increased. The soot, HC, and CO emissions decreased with higher injection pressure and earlier injection timing, while the HC emission increased significantly with higher premixed ratio. With the increase of EGR, the soot and NOx emissions decreased while the CO and HC emissions increased significantly. In the modelling investigations, the primary reference fuel (92% isooctane and 8% n-heptane, PRF92) was used as a surrogate of commercial RON92 gasoline fuel for combustion prediction. The combustion and emission characteristics were well predicted in the simulations. The control parameters, including intake temperature and pressure, premixed ratio, injection pressure and timing, as well as EGR, on the GCI combustion process were further elucidated.