A study was conducted to control the ferroelectric domain structure in BiFeO3 (BFO) films through the use of vicinal SrTio3 (STO) substrates. The ferroelectric domain structure of an epitaxial BFO films on STO substrates with different orientations is modeled using the phase-field method. The ferroelectric polarization variants in the films were characterized by piezoelectric force microscopy, where structural variants were analyzed and confirmed by X-ray diffraction. Morphology and local piezoelectric properties of films were investigated using an atomic force microscopy (AFM). X-ray scattering was used to confirm the domain architecture to verify the structural properties of the films. The downward directed polarization variants are observed, indicating the existence of a self-poling effect of the films.