Composite insulation materials were prepared with inorganic cementitious materials and different kinds of lightweight aggregates， i.e. normal expanded polystyrene（EPS） particles， surface treated EPS particles， flame retarded EPS particles， surface treated EPS particles and cenospheres mixture. Effect of different lightweight aggregates on performance of composite insulation materials was investigated. Results show that tensile strength and compressive strength of composite insulation materials are enhanced by 57% and 31% respectively after EPS particles are surface treated, and thermal conductivity of composite insulation materials is reduced slightly. Peak heat release rate（pHRR） is decreased by 41.9% compared with the composite insulation materials with normal EPS particles as lightweight aggregates(control sample). Performance of composite insulation materials can meet the standard requirements with cenospheres volume fraction of 30% in lightweight aggregates. For composite insulation materials with this mixed lightweight aggregates，flame retardancy is increased significantly， pHRR is decreased by 85.9% compared with the control sample and total heat release（THR） is 0.7MJ/m2， which has reached class A1 non combustible material standard.