The silazane compounds was synthesized through convenient and efficient method. Using it as a curing agent， lightweight components and ablative dimensional components were studied separately. Finally， a low-density heat-resistant coating for reusable aircraft with excellent thermal stability， high dimensional stability at high temperatures and good ablation resistance was obtained. The results indicates that the density and mass retention rate of the heat-resistant coating tend to stabilize after a finite number of static ablations， and the mechanical properties meet the usage requirements. The coating has undergone up to 10 times of quartz lamp ablation assessments， and its thermal insulation performance has remained unchanged. In addition， after 5 times wind tunnel ablation assessments， ablation resistance and thermal insulation performance of heat-resistanct coating has remained unchanged， which shows that heat-resistant coating can still provide good thermal protection for aircraft after a finite number of repeated use.