Layered and rod-like K3Ti5NbO14 was synthesized via the solid-state chemistry, and it was exfoliated into nanosheets through a novel mechanical cleavage technology. X-ray diffraction was utilized to determine the phase changes of all the specimen during the total process, and the microstructure of the samples was analyzed by scanning electron microscope and transmission electron microscope. The formation mechanism was also discussed in detail, the results indicated that the compression and shearing should play a main function in the crack and the cleavage of the aggregated layered compound. UV-vis absorption spectroscopy was used to monitor the consecutive buildup of the (PEI/Ti5NbO14)(n) film. The resulting quasi-linear increase at the top absorbance as a function of the sequential assembly number for the multilayer film indicated that the nanosheet had deposited uniformly in each dipping cycle. The photocatalytic activity of K3Ti5NbO14-related products was examined. Compared with original layered compound, nanosheet precipitate had good property under irradiation of ultraviolet light.