Lead-free piezoelectric ceramics of (K-,K- Na)NbO3 modified by Li, Ta, and Sb (KNN-LTS) have been widely investigated recently. In this research, this optimized composition of KNN-LTS ceramics near polymorphic phase transition is explored according to the linear combination rule (LCR) for the first time. Changing with the compositions monotonically, remanent polarization (P-r) decreased monotonically, whereas permittivity (epsilon(T)(33)/epsilon(0)) increased similarly. The increase in either epsilon(T)(33)/epsilon(0) or P-r initially enhances piezoelectric coefficient d(33) before reducing it because d(33) can be improved by epsilon(T)(33)/epsilon(0) and P-r. The optimal composition of (Na0.52K0.4415Li0.0385)(Nb0.8735Ta0.064Sb0.0625)O-3, predicted by LCR, exhibits the excellent electric properties of d(33) = 359 pC/N, k(p) = 42%, thus suggesting that the LCR effectively predicts the electric properties of the KNN-LTS ceramics.