Abstract: Thermal insulation is of great strategic importance for energy saving and emission reduction, and energy consumption. In this paper, the surface modification of hollow glass microbeads (HGMs) with boehmite sol was used to introduce the air cavity structure to improve the thermal insulation performance of the coating and to prepare a high-performance water-based composite coating that can be produced continuously. The microscopic morphology and structure of the composite microspheres were analyzed by FTIR, XRD, SEM and other characterization methods. Thermal weight loss analysis, thermal conductivity, infrared thermography and other technical means were used to systematically study the microstructure, comprehensive performance, thermal insulation and heat preservation mechanism of the coating. The results show that the surface modification of HGMs is successfully carried out by boehmite sol, and HGMs@Al₂O₃ retains the basic structure and characteristics of HGMs, enhances the interfacial compatibility with the aqueous polymer matrix, and solves the practical problem of poor interfacial bonding between HGMs and the aqueous matrix, resulting in large fluctuations of its thermal conductivity. Compared with the composite coating without added thermal insulation filler, when the content of HGMs@Al₂O₃ is 7wt%, it reaches the over-permeability threshold, and the comprehensive performance of the coating is the best, which significantly improves the thermal insulation of the composite coating and reduces the thermal conductivity by 58.7%. The application potential and commercialization prospect are huge.