In the bearing cavity for oil and gas lubrication, there will occur a collision between the oil droplet and oil film on the wall, which affects the lubrication of bearing cavities and the heat transfer. In this paper, the high-speed camera is utilized to make the visualization research for the phenomenon of the oil droplet impacting the oil film on the wall. Furthermore, the form and dynamics of the oil droplet are investigated by changing the wall roughness and Weber number. The results show that: the impact morphology can be divided into 4 modes based on the correlation between dimensionless wall roughness and Weber number; the splashing phenomenon is caused by the combined action of K-H (Kelvin-Helmholtz) instability and P-R (Plateau-Rayleigh) instability; the increase of dimensionless wall roughness and Weber number significantly enhances the instability of the crown edge, thereby intensifying the splashing degree. In conclusion, dimensionless wall roughness and Weber number have a significant impact on the morphological evolution and dynamic characteristics of the droplet after impact.