The Relationship between the Piezoelectric Properties and Crystal Lattice Deformation and Distortion Resulting from the Li Substitution in LiXNa0.52K0.48-XNbO3, Alkaline Niobate-Based Perovskite Ceramics of (Li, Na, K)NbO3, Was Investigated. the Lattice Parameters of the Sample with a Li Content X = 0.05 and Having a Monoclinic System with Space Group PM Were a = 3.9789(6) Å, B = 3.9385(5) Å, C = 4.0134(6) Å, and B = 90.305(4)º. the ET33/e0, Kr, and -D31 Values of the Sample by Poling in the Monoclinic System Were 450, 44.6%, and 57 PC/N, Respectively. on the other Hand, the ET33/e0, Kr, and -D31 Values of the Sample by Poling in the Tetragonal System Were 600, 38.7%, and 56 PC/N, Respectively. the Remarkable Piezoelectric Properties of these Ceramics Can Be Attributed only to the Low Symmetry of their Monoclinic System, which Is a Subgroup of aMm2 and P4mm. Li0.05Na0.52K0.43NbO3 Ceramics with a Monoclinic System Were Observed to Have the Unique Piezoelectric Characteristics.