Nylon 6 film (IAF film) and powder were iodinated with 0.2, 0.4, 0.6 and 1.0 N of I$_2$/KI aqueous solutions, and the iodinated powder was used to make the films iodinated before forming (IBF film). The crystal structure and drawability of the two kinds of films were investigated through X-ray diffraction, DSC, IR analysis, and tensile test. In the case of IAF films, not only the 4 steps in formation of the nylon 6-iodine complex crystal with increasing concentration of I$_2$/KI but also the existence of $I^-_5$ ions over the 2nd step were confirmed again by X-ray diffraction and DSC analysis. In the case of IBF films, however, the formation of the complex crystal was not confirmed. but the formation of new $alpha$- and ${gamma}$-crystals of nylon 6 was confirmed by X-ray diffraction, IR, and DSC analysis. The tensile behavior of IAF showed the much lower yield and breaking loads and the much higher breaking elongation in comparison with untreated film, but the elongation of IBF films was lower though the load was lower than that of IAF films. The maximum draw ratio and initial modulus were 3.5 and 0.88 GPa for the untreated film, 9.5 and 9.48 GPa for the drawn IAF films after removal of iodine, and 5.5 and 1.16 GPa for the drawn IBF films after removal of iodine. The maximum values of draw ratio and initial modulus could be achieved from the films iodinated with 1.0 N I$_2$/KI solution, and at drawing temperatures of 4$0^{circ}C$ and 60% for IAF and IBF films, respectively.