For the first time, a new fluoroamine compound was synthesized by aminating the perfluoroacrylate compound. The synthesized fluroamine was used to modify the surface of polyacrylonitrile (PAN) nanofibers and the fog harvesting ability of the modified nanofibers was investigated. The results showed that the maximum fog harvesting capacity (335 mg/cm2/h) was achieved at the time, the temperature and the amount of fluoroamine compound of 3 h, 95 °C and 8% (w/w) in the modification process, respectively. The fog harvesting capacity of fluorinated nanofibers was much higher than that of untreated PAN nanofibers (31 mg/cm2 h), which is due to the superhydrophobic nature of fluorinated nanofibers. The superhydrophobic property of the fluorinated nanofibers was evaluated by investigating the wettability properties including water contact angle and surface energy of prepared nanofibers. Furthermore, the average surface roughness of nanofibers was determined as 41.8 and 51.2 nm for untreated and fluorinated nanofibers, respectively. The result indicated the superhydrophobic property of prepared nanofibers due to the increased surface roughness, high water contact angle (159°), and low surface energy value (17.1 mN/m). Moreover, it was found that the fog harvesting capacity increases with increasing the distance of the nanofibers mat from humidifier because of increasing the water mobility. The results of nanofiber characterization showed that the fluoroamine molecules were covalently grafted onto the nanofiber surface through the formation of amidine group. Also, at the optimum condition, deposition of a layer with the thickness of 17 nm on the nanofiber surface was detected. It was found that increasing the thickness of fluoroamine layer enhanced the hydrophobicity and fog harvesting capacity of nanofibers up to a certain level. The total surface area of nanofibers was decreased after the grafting process because of increasing the nanofiber diameter.