Mg/Al layered double hydroxide with two-dimensional (2D) nanostructures was synthesized by a hydrothermal technique. The morphology and aspect ratio of Mg₄Al₂(OH)₁₄3H₂O were controlled by the concentration and kinds of the hydrolysis agent, and temperature. The aspect ratio of Mg₄Al₂(OH)₁₄3H₂O layered double hydroxides with the 2D hexagonal crystal structure was tailored from about 12.6 to about 45.7. The intercalated CO₃^2- anions of the synthesized 2D Mg₄Al₂(OH)₁₄3H₂O layered double hydroxides were exchanged to NO₃^- anions. The bulk 2D Mg₄Al₂(OH)₁₄3H₂O layered double hydroxides with the increased space between two layers due to the anion exchange were exfoliated in a formamide solution. The aspect ratio of the exfoliated 2D Mg₄Al₂(OH)₁₄3H₂O layered double hydroxides increased to 570.3.