The invention discloses a method for preparing a two-dimensional material by using waste grease. The method takes waste grease as a raw material, insoluble solid particles in the waste grease are extracted, and the insoluble solid particles are subjected to reinforcement through a liquid-phase delamination layer, and separation and purification to obtain the two-dimensional material. The method has the advantages of simple and easy process, controllable quality, low regeneration cost by changing waste into valuables, and high product added value, has practical popularization and application value, and can generate obvious social, economic and environment benefits.