Controlled blasting techniques are used to control overbreak and to aid in the stability of the remaining rock formation. The less competent the rock mass itself is, the more care has to be taken in avoiding damage. Presplitting is one of the most common methods which is used in many open pit mining and surface blast design. The purpose of presplitting is to form a fracture plane across which the radial cracks from the production blast cannot travel. Presplitting should be thought of as a protective measure to keep the final wall from being damaged by the production blasting. The purpose of this study is to investigate the effect of presplitting on the generation of a smooth wall in a rock domain under a surface blast process. The 2D distinct element method was used for the simulation of presplitting in a rock slope. A simple blast load history was applied to the inner wall of each blasthole. Important parameters that were considered in the analysis were stress tensor and fracturing pattern. The analysis results show that the blast loading magnitude and blasthole spacing are significant parameter affecting the final results.