Abstract: With the rapid development of Chinese economy and urbanization, sludge production in sewage treatment plants rises rapidly. It is very important to properly dispose of the sludge. The preparation of sludge-based foam insulation materials can utilize the sludge to meet the needs of Chinese sustainable development strategy. The type and proportion of the foaming agent were studied to determine the optimum material compositon and proportion. On this basis, orthogonal experiments were carried out to optimized the preparation process of sludge-based foam insulation materials. The effects of sludge addition, cement addition and water-solid ratio on the properties of foaming insulation materials were studied, and the preparation process was optimized. The results showed that OP emulsifier-10 of 0.6% and cellulose ether of 0.3% were the best for foaming. Through comprehensive analysis of multiple performance indicators, it was concluded that the order of the influencing factors of sludge-based foaming insulation material preparation was water-solid ratio>sludge addition>cement addition. The optimum ratio of raw materials was sludge of 12.5%, cement of 55.5%, water-solid ratio of 0.5. Under this optimum ratio, density, compressive strength and thermal conductivity of the prepared insulation materials were 624.4 kg/m³, 0.32 MPa and 0.072 W/(m·K), respectively, which met the requirements of national standard for density A07, compressive strength C0.3 for inorganic foaming materials (JG/T 266—2014).