Abstract: Janus nanoparticles (JNPs) possess great potential in recovering the residual oil from reservoirs, however, the fundamental interaction mechanisms among nanoparticles, the oil, and reservoir wall characteristics remain to be elucidated. In this work, models of oil trapping grooves with different geometric features are subjected to molecular dynamics simulations for investigating the influences of roughness parameters on oil displacement dynamics by JNPs. Four key surface geometry parameters and different degrees of surface hydrophobicity are considered. Our results indicate that JNPs hold an outstanding performance in displacing residual oil on weakly to moderately hydrophobic surfaces. Overall, smaller entry and exit angles, the larger aspect ratio of the oil trapping grooves, and a bigger tip length of the rough ridges lead to superior oil recovery. Among the key geometric parameters, the aspect ratio of the oil trapping grooves plays the dominant role. These insights about the interaction of surface properties and JNPs and the resulting trapped oil displacement could serve as a theoretical reference for the application of JNPs for targeted reservoir conditions.