The flexible aerogel monoliths were prepared by the hydrolysis and condensation of methyltriethoxysilane
(MTES),followed by supercritical drying. The influence of concentration of precursor on the chemical composition,
microstructure,flexibility and thermal stability of aerogel were investigated. It is shown that the degree of cross
linking of aerogel molecule, which was prepared by the precursor of MTES and showed excellent flexibility was declined
because of the existence of methyl groups. With the reduction of concentration of precursor, the degree of compactness
of aerogel particles declined, which is responsible for the enhancement in the flexibility of the aerogels, the
number of Si-OH increased and the thermal stability of aerogel exhibited the same tendency.