High density fine grain (1−x)BiScO3–xPbTiO3 ceramics were successfully prepared by two-step sintering and their ferroelectric properties were investigated. Experimental evidence indicates the existence of a morphotropic phase boundary at the composition zx=0.635, which exhibits a piezoelectric coefficient d33 of 700 pC/N at room temperature, significantly higher than the reported values to date. Furthermore, a higher electromechanical coupling factor Kp=0.632 and a larger remnant polarization Pr=47.3 µC/cm2 were obtained. The paraelectric-to-ferroelectric phase transition occurs at 446 °C, slightly lower than in the coarse grain ceramics with a similar composition, suggesting a grain size effect. The local effective piezoelectric coefficient d33* was estimated to be 795 pC/N at 2.29 V, measured by scanning probe microscopy. Further atomic force microscope observation revealed the existence of 90° domains of about 60–70 nm in width, confirming the previous results that small domain structure enhances the piezoelectric properties.