Fog water collection is the process of converting gaseous fog into liquid water,which has important research value. The control of condensation efficiency is crucial factor in the collection of fog water. Improving condensation efficiency is mainly related to the thickness of the boundary layer and effective renewal on the substrate surface. In this paper, inspired by the back structure of desert beetles, a Janus film with bump structure on the surface of aluminum foil is prepared by femtosecond laser micro-nano processing and surface chemical modification, which could achieve efficient droplet condensation. The experimental results show that compared with the flat Janus film, the water collection efficiency of the bumpy Janus film is increased by 80%. More importantly, the bumpy Janus film can capture a horizontal fog flow and adapts harsh natural environment.