Two different local density approximation (X{alpha} and Kohn-Sham exchange and Perdew-Zunger correlation) of the density funcitonal method have been used to calculate structural and electronic properties of six kinds of polyfluoroethylene, including polytetrafluoroethylene (PTFE), poly(1,2-difluorethylene) (PDFE), and others, for several different dihedral angles. For PTFE and PDFE, all the geometric parameters are optimized simultaneously in the stable helical conformation. The position of the minimum and the depth of the potential well are in good agreement with the experimental results. The stable helical conformation are found for PTFE and PDFE. For PDFE a shoulder close to the stable gauche conformation is found in the energy curve. The potential curves of another four kinds of polyfluorethylene are studied in detail close to the planar conformation. The side fluorine atoms strongly affect the conformation and the electronic structure. The band structure of PTFE and PDFE in optimized geometry and the other PFEs in planar zigzag conformation are calculated in good agreement with experimental results.