The dielectric and ferroelectric properties of sol-gel derived BiScO3–PbTiO3 thin films prepared by two different kinds of crystallization processes were studied. The film prepared by a single crystallization had a higher remanent polarization and dielectric constant than the one prepared by a multiple crystallization. The remanent polarization and dielectric constant were 50 μC/cm2 and 1609 for the single crystallization sample, and 40 μC/cm2 and 1429 for the multiple crystallization one. The investigation of the Rayleigh law revealed that the film prepared by a multiple crystallization, processed more irreversible domain wall motion contribution and less reversible contribution with respect to the one by a single crystallization. This was attributed to the layer-to-layer interfaces generated during the multiple crystallization processing, which acted as energy barrier and had a pinning effect on the domain wall motion, resulting more irreversible domain wall motion.