Rietveld refinement is used to investigate the crystal structure of prepared (0.965 - x)(K0.48Na0.52)NbO3-xBiInO(3)-0.035-(BiO5Na0.5)ZrO3 (KNN-xBI-BNZ) ceramics. From refined results, the distortion degree of crystal structures in KNN-xBI-BNZ ceramics presents a rising trend with BiInO3 modification, which is in keeping with the results of diffuseness. The spontaneous polarization (P-s) is also calculated using refined structural parameters. The submicron domains are observed when x = 0.004, which presents good electrical properties (d(33) = 317 pC/N, T-c = 336 degrees C) simultaneously. Excellent thermal stability of ceramics modified with BiInO3 is observed in a broad temperature range.