The invention discloses a 3D printing aramid fiber aerogel, and a preparation method and an application thereof. The preparation method comprises the following steps: uniformly mixing aramid nanofibers and a solvent to form an aramid nanofiber dispersion; and carrying out sol-gel conversion and drying treatment through a freezing-direct writing forming technology to obtain the 3D printing aramid fiber aerogel. Surface hydrophobic modification and filling modification are respectively carried out on the 3D printing aramid aerogel to respectively obtain a hydrophobic material, a photochromic material and a temperature response material. The preparation method of the 3D printing aramid fiber aerogel has the advantages of wide dispersity, low energy consumption, quick low-temperature response,high printing precision, simple process and short flow, and the obtained 3D aramid aerogel has the advantages of ultralow density, good mechanical properties and structural designability, can be applied to the fields of heat preservation and insulation, catalysis, separation / adsorption, sensing, soft robots and the like, and greatly expands the application range of 3D printing and aramid aerogel.