Optical properties of crystal violet doped polymethylmethacrylate (PMMA) films were studied. Absorption and transmission spectra were measured from UV-Visible spectrophotometer. Reflection spectra was calculated for all samples. CV- PMMA samples were prepared by casting method. CV solution was 0.5×10-4mol/liter, and different amount of this solution as (2, 5, 10, 15, 25, 35, and 40)ml were added to get CV- PMMAfilms. Energy band gap was calculated for CV dye equal to 2eV and for PMMA5eV and calculated for all CV-PMMAfilms which about (1.92- 1.98)eV.Also, all optical constants (absorption coefficient, extinction coefficient, refractive index, real and imaginary dielectric constant) were measured for all samples.Morphology behavior and FTIR spectrumand X-ray diffraction were illustrated and compared with other researchers.