In order to develop a new approach to prepare high-density genechip with in situ synthesis, the authors propose a way to synthesize DNA microarrays by means of deprotection with acid generated by electrolyzing some substances in solvent. Water can release protons when electrolyzed at 2.0 V, leading to the increase of acidity on anode. Therefore, DMT protecting group can be removed. The relationship between the synthesis efficiency and other conditions, such as electrolysis time, concentration of electrolyte, concentration of water and so on was measured. It was found that the longer the electrolysis time, the higher the deprotection efficiency. The concentrations of electrolyte and water have little influence on deprotection efficiency.