To meet the commercial requirements of inorganic heat insulators,the mixture of diatomite and Ca(OH) 2 are evenly dispersed,mold-compacted,and then hydrothermally solidified due to the formation of tobermorite under an autoclaved process.Systematic investigations of the preparation conditions (including mix ratio,autoclaved factors,mold pressure,etc)were carried out to optimize the serving properties of such toberrnorite-based products.As a result,a compressive strength of more than 30 MPa was realized for the specimen in high density( about 1.30( g·cm-3) ).On the contrary,the specimen in light weight for example 0.63 ( g ·cm-3 ) typically showed a thermal conductivity of around 0.12 ( W· m-1· K-1 ).The present work developed a feasible way to produce and to control the serving properties of diatomite-based heat insulators by a process of hydrothermal solidification,in which the optimized value of Ca/Si ratio was proposed to be 0.6 ～ 0.7,while the water content is 25 ％ in weight,and hydrothermal reaction is performed at 180 ℃ for no more than 24 hours.