Ferroelectric SrBi1.4La0.6Ta2O9 (SBLT) thin films were grown onto Pt/Ti/SiO2/Si substrates by pulsed-laser deposition. With the aid of X-ray diffractometry, piezoresponse scanning probe microscopy, and ferroelectric-property measurements, a correlation between microstructure, as well as domain structure and ferroelectric properties, was established. Excluding the effect of preferential orientation on ferroelectric properties, the increase in remanent polarization was attributed to distortion of the perovskite-like sublattice and atom displacement. Despite the co-instantaneous observation of a 90degrees domain and slight fatigue behavior in the SBLT films, the 90degrees domain-wall clamping did not seem to account for the fatigue in the SBLT films. Instead, strain-stress aggravation of the SBLT sublattice, due to the substitution of La3+ into Bi3+ sites, decreased the self-regulated flexibility of the (Bi2O2)(2+) layers and caused fatigue in the SBLT.