Temperature scaling of dynamic ferroelectric hysteresis for the morphotropic phase boundary (MPB) compositions in xBiScO(3)-(1-x-y)PbZrO3-yPbTiO(3) (xBS-(1-x-y)PZ-yPT, 0.018 <= x <= 0.264) ternary system was systematically investigated. The power-law relation was obtained for remanent polarization P-r and temperature T, that is, P-r proportional to T-beta. It is interesting to find that the power-law exponent beta could be modulated by BiScO3 content x. With the increase of x from 0.018 to 0.264, beta varies from -1.09398 to 2.44147. Transition of beta from negative to positive produces in the vicinity of 0.054BS-0.476PZ-0.470PT ceramic. At this composition, the magnitude of beta is very close to zero with value of only -0.01567, implying an almost temperature-independent polarization characteristic of the ceramic. Comparing with the conventional PZT-based piezoelectric ceramics that usually with negative exponent beta, when x > 0.054, the xBS-(1-x-y)PZ-yPT ceramics show positive beta value, so that the ferroelectric polarization is enhanced with increasing temperature. Such a positive temperature dependence of ferro-/piezoelectric property makes the ternary system a promising candidate for high-temperature applications.