Fluorinated ethylene propylene (FEP) film is an attractive candidate for mitigating target debris in high-power laser systems due to its remarkable advantages such as low cost, low absorption, and high damage threshold. However, the inert surface with bad wettability presents an enormous challenge to realize optical antireflection. In this Letter, we experimentally demonstrate that broadband antireflection of FEP film can be achieved through combining oxygen plasma treatment and solgel coating techniques. By optimizing the plasma treating time and withdrawal rate during the coating process, the treated FEP film has 4.7% enhanced transmittance compared to the untreated sample. In this case, transmittance over 99% with wide wave bands ranging from 600 to 950 nm is achieved. The mechanism of broadband antireflection was revealed by investigating the fluorocarbon groups on the FEP surface. The applicable wave band of antireflective FEP film can be designed at will by changing plasma-treating conditions, which could open up a new avenue in the field of laser debris mitigation.