Plate-like NaNbO3 (NN) templates have been successfully synthesized via a two-step molten salt method using K2CO3 as a raw material at 970 °C, which is below the topochemical reaction temperature using Na2CO3 as the raw material (higher than 1000 °C). The synthesized plate-like NN particles have a higher aspect ratio with a thickness of 0.5-1 μm, a width of 5-10 μm and a length of 15-25 μm. In this process, we found that Na2CO3 or K2CO3 plays an important role in removing the (Bi2O2)²⁺ layers in the substitution process and the final composition is decided by the type of molten salt. Using KCl as molten salt and Na2CO3 or K2CO3 as raw material, the (Bi2O2)²⁺ layers could be removed by Na2CO3 or K2CO3 and K⁺ ions can be incorporated into the template during the topochemical reaction and thus (K, Na)NbO3 (KNN) plate-like particles can be fabricated. The growth process is reasonably elucidated by this growth mechanism.