As the global climate tends to become more extreme, high-performance thermal management materials are important for the comfort of human existence.Cellulose-based aerogels have become a hot research hotspot due to their abundant raw materials and good mech. properties.Herein, cellulose/silica-aluminum composite aerogels (CSAL) with organic-inorganic structures were obtained by in situ formation of silica-aluminum aerogel nanoparticles via a two-step sol-gel process, which was prepared by dissolving cotton pulp in the ionic liquidRelated properties are investigated with Fourier transform IR spectroscopy, SEM, UV-visible spectrometer, N2 adsorption, compression tests, thermogravimetric anal., and ignition tests.The resulting CSAL samples have low d. (0.112-0.133 g/cm3), high sp. surface area (252.65-464.02 m2/g), good mech. properties, and excellent transmittance (>60 %).Thus, the as-prepared high-performance cellulose/silica-aluminum composite aerogel films with flexible, transparent, flame retardant, which have great potential for application in lightweight energy-efficient buildings, household equipment and other fields requiring thermal insulation.