In order to investigate the jet characteristics of a droplet impinging on an overlapped oil film in a deep pool, the kinetic properties of the jet evolution and the generation of sub-droplets during the impinging process are investigated by physical experimental methods. Most of the kinetic energy carried by the droplet is converted into potential energy, surface energy and capillary energy of the cavity, and a small part is converted into viscous dissipative energy. The experimental results show that the immiscible properties of the droplet-oil film-liquid pool leads to a more complex jet evolution process, with the emergence of two jet regimes, a singular jet and a compound jet, which are mainly dominated by the Froude number. Compound jet sub-droplets arise due to the occurrence of Rayleigh-Plateau instability in the upward jet. As the Froude number increases, increasing droplet kinetic energy induces a rise in the height of the jet, and the droplets penetrate the oil film, deform by sufficiently mixing with water in the deep pool, and break up during the dive. The thickening of the viscous oil film acts as a buffer for the droplets, reduces the maximum height of the jet, and hinders sub-droplet generation. The results of this study contribute to further understanding of the jet dynamics of droplet impacts in a complex covered oil film surface environment, and reduce the generation of toxic aerosols.