The invention discloses a brake with a self-compensation function and a braking method of the brake, and belongs to parking braking equipment. The brake comprises a brake disc and brake units arranged on the two sides of the brake disc, each brake unit comprises baffles, a piston, an adjusting taper sleeve, a piston push rod and a friction plate, a caliper body and the baffles form an annular mounting space, a piston can axially moving left and right along the annular mounting space, the adjusting taper sleeve is arranged on the side, away from the baffles, of the inner surface of the piston in a sleeving mode and can be kept expanding or contracting in the radial direction of the mounting space, one end of the piston push rod is mounted on the adjusting taper sleeve in a sleeving manner, the piston push rod is in clearance fit or interference fit with the adjusting taper sleeve, and the friction plate is connected with the other end of the piston push rod and is suitable for pressing the brake disc. The brake belongs to a fixed parking brake, the pressing force of a disc spring is completely converted into the parking braking force through hydraulic oil return, and due to the fact that the parking braking force is not consumed by other parts, the braking efficiency is high, an external power source is not needed, and automatic abrasion compensation can be achieved.