BaSO₄ is an excellent thermal insulation filler，but necessary surface modification of BaSO₄ is required for its unideal thermal insulation effect when applied in a single form. BaSO₄/SiO₂ composite powder was prepared by sol-gel method using tetraethyl orthosilicate（TEOS） as surface modifier. BaSO₄/SiO₂ thermal insulation coatings were prepared by using the prepared composite powder as thermal insulation filler and waterborne polyurethane emulsion as film forming material. The structure and morphology of the prepared composite powder and coating were characterized by XRD，FT-IR，SEM and EDS. The effects of TEOS addition on the solar reflectance，near-infrared reflectance，hemispherical emissivity and thermal insulation properties of the coating were investigated. The results showed that，with the increasing of TEOS addition，the solar reflectance and near-infrared reflectance of the coating increased gradually，the hemispherical emission and the thermal insulation temperature difference increased first and then decreased. When the mass fraction of TEOS was 25%，the solar reflectance，near-infrared reflectance，hemispherical emissivity and thermal insulation temperature difference of the coating were 81. 88%，79. 79%，0. 89 and 19. 98 ℃，respectively，showing good thermal insulation effect.