The invention discloses a flaky activated carbon material. The microscopic morphology of the flaky activated carbon material is flaky; further, the size of the particle diameter of the flaky activated carbon material is adjustable and controllable; the adjustable and controllable range of the transverse dimension of the particle diameter is 0.1 to 50 microns; the adjustable and controllable range of the thickness of the particle diameter is 0.05 to 2 microns. The invention also discloses a preparation method and application of the flaky activated carbon material. The flaky activated carbon material provided by the invention is used as an electrode material for a double-electric-layer capacitor; the obtained double-electric-layer capacitor is enabled to have excellent electric performance.