A new method is presented for predicting the distribution of vector scattered fields of multilayer optical coatings. The scattering properties of film stacks with various interface cross-correlation models are discussed according to the statistical principles. The theory has been related to the familiar concepts of thin film optics, and simple results are obtained. It is shown theoretically that even though the optical parameters of the multilayer optical coatings are the same, the scattering losses can be quite different due to the different interface cross-correlations. Measurements of the scattered field distribution of optical films have also been made, and from them the interface cross-correlations of the multilayer optical films are determined according to the vector scattering theory.