The invention discloses a method for preparing graphene through electrochemical cathodic disbonding graphene sheets by taking DTAB as electrolyte. The method is characterized by comprising the following steps: firstly, preparing materials; secondly, preparing electrical disbonding liquor; thirdly, assembling an electrical disbonding device; fourthly, performing electrical disbonding; fifthly, filtering and washing; sixthly, performing ultrasonic dispersion; seventhly, performing freeze drying, so as to obtain an aqueous solution of graphene, and performing freeze drying, so as to obtain graphene powder. The method has the advantages that raw materials for preparation are simple and easy to obtain, the method is easy to operation, the cost is low, the technical process is simple, steps areless, the production cycle is short, the defect level of the formed graphene is low, the number of layers is small, and the graphene is very suitable for industrial production.