The invention provides a secondary 
drying method for preparing hydrophobic aluminum-
silicon aerogel heat-insulation materials. The secondary 
drying method includes steps of S1, preparing aluminum solby means of 
hydrolysis by the aid of 
acid catalysis processes, and impregnating the aluminum 
sol in 
fiber reinforced material gel to obtain 
fiber reinforced aluminum gel; S2, sealing and aging the gel, carrying out 
ethanol supercritical drying and then carrying out heat treatment; S3, immersing 
fiber / aluminum 
aerogel composite materials in alkaline solution, carrying out surface alkaline treatment, carrying out centrifuging and then carrying out 
drying; S4, preparing 
silicon sol by means of 
hydrolysis by the aid of 
acid catalysis processes, uniformly impregnating the 
silicon sol in fiber / aluminum 
aerogel composite material gel to obtain composite materials; S5, immersing the composite materials in 
alcohol solvents, sealing and aging the composite materials in the 
alcohol solvents, carryingout solute replacement on the composite materials in the 
alcohol solvents, then immersing the composite materials in surface modifier solution, carrying out surface treatment on the composite materials in the surface modifier solution and then carrying out secondary 
ethanol supercritical drying to obtain the aluminum-silicon aerogel heat-insulation materials with the hydrophobic performance. 
Silicon gel is available on pores of the composite materials obtained at the step S4. The secondary drying method has the advantages that the mechanical properties of the hydrophobic aluminum-silicon aerogel heat-insulation materials can be obviously improved by the aid of the secondary drying method, the hydrophobic aluminum-silicon aerogel heat-insulation materials have the hydrophobic properties, and the excellent high-temperature heat-insulation performance can be kept.