Fe/MgO nanocomposite films are prepared using pulsed laser deposition, and the effects of pulse number on the structure, composition, and optical properties of the composite films are studied in this paper. X-ray diffraction analysis shows that a diffraction peak with a crystal plane orientation of (211) appears when the pulse number of the deposited Fe nanoparticles is greater than 500, confirming the existence of Fe, Mg, and O elements in the composite film; part of the Fe nanoparticles in MgO film is oxidized, thus existing in the elemental and oxidized states (content ratio of ~3∶2). High-resolution transmission electron microscopy analysis shows that when the pulse number is 100, Fe nanoparticles with an average particle size of ~2.73 nm are uniformly distributed in an ellipsoid shape in the MgO film, and the average spacing between Fe nanoparticles is ~1.75 nm. Ellipsometry analysis shows that the refractive index and dispersion sensitivity of the Fe/MgO nanocomposite films increases as the pulse number increasing when the wavelength is less than 365 nm. Ultraviolet-visible spectral analysis shows that Fe/MgO nanocomposite films exhibit an obvious ultraviolet narrow-band antireflection phenomenon in the wavelength range of 190-235 nm compared with pure MgO films;the transmittance of the composite film at 197 nm is ~69.4%.