Abstract: The optical properties of inhomogeneous coatings which were prepared by double-source linear co-evaporation, were discussed and compared with that of homogeneous coatings. The influences of the refractive index distributions, maximum index-departure and coating thickness-deviation on the optical characteristics of coatings were discussed respectively. Analysis results show that the refractive-index distribution regularity error has an important influence on the wavelength application range of the coatings, and the thickness error or index-departure has a vital influence on the optical properties of inhomogeneous coatings．