This paper presents nano processing mechanism of nano-sheet with Atomic Force Microscope (AFM). The nano-sheet is structured potassium niobates with 2 nm of thickness, and the anisotropy in the direction of 90° existed on the nano-sheet surface is figured out from the experiments. This anisotropy is a huge influence in production to high accuracy of the shape and size with nano-sheet processing. This processing characteristic is investigated from Hertzian contact theory and processing energy. Taking account of the anisotropy, experiments are also examined for the optimal processing condition. The FFT analysis from Lateral Force Microscope (LFM) shows processing force appeared periodically and the increasing of frequency period is occurred by increasing of processing load. The nano processing mechanism is performed the instability when the processing force is weakly and short frequency. Next, the groove processing is conducted in order to prove these mechanisms and it became clear that groove width is spreaded because load and coarseness is increased. The stability processing region of the minimum load for groove processing approximately equal to around 800 nN from our experiments. Finally, the high precision groove processing with 28 nm of maximum width is attained by using this processing condition.