Abstract: Waterborne polyurethane(WPU) emulsion modified by antimony doped tin oxide(ATO) nanoparticles(APU) was prepared with isophorone-diisocyanate(IPDI),polyether diol(N-210),dimethylol propionic acid(DMPA),diethyleneglycol(DEG),trimethylolpropane(TMP) and ATO nanoparticles.Particle size testing and electron transmission microscopy observation showed that ATO nanoparticles was dispersed well in WPU and emulsion particle size was less than 100 nm.FTIR analysis suggested that chemical interaction existed between ATO nanoparticles and WPU.It is found from thermogravimetric analysis(TGA) that the addition of ATO nanoparticles had improved the thermal stability of WPU with the maximum 20℃ increase of the maximum thermal decomposition temperature.UV-visible-near infrared absorption and thermal insulation performance tests showed that the film's transmittance at 800~2500 nm gradually decreased with the increase of the ATO addition amount,while the coating transmittance in the visible region was still more than 70%.Moreover,the thermal resistance rate increased from 1.34×10^-2 m²·℃/W to 3.17×10^-2 m²·℃/W.