Local anodic oxidation with atomic force microscopy has became a major technique for nanofabrication. Finding a proper and efficient way to assemble the discrete dots or lines into one uniform layer with specific shape is critical for application. The aim of this paper is to find a more flexible way to analyze and guide LAO procedure. The threshold pitch for assembling a uniform line is further studied with optimum method. The threshold pitch is close related the tolerance of the overlapped profile. Under a certain allowance fluctuation, the equivalence relation between line and dots is defined. Without lose accurate, a simplified equation to calculate overlapping profile for equivalent oxide line and layer has been found. With the equivalence relation, the oxide line and layer can be disassembled into array of dots. Using equivalence dots is a simple, flexible and efficient way to analyze and guide LAO procedure. Forming a close curve and a layer with round shape are taken as examples to describe the strategy. The direction for developing a CAD/CAM for nano oxide layer fabrication is proposed.