The properties of moulded quartz phenolic composites are studied by the methods of mechanical and physical tests,comparing with moulded high silica phenolic composites. The result shows that moulded quartz phenolic composite not only has good mechanical property,but also has much more lower thermal deformation in the environment of low enthalpy,low heat flux and long-time ablation as the property of half linear expansion coefficient comparing with moulded high silica phenolic composite.