Abstract: The PtSn nanofluid was synthesized by microfluidic method, using EG as the base liquid and reducing agent, SnCl₄·5H₂O and H₂PtCl₆·6H₂O as oxidants. Different proportions polyvinylpyrrolidone (PVP) were added as surfactants. The absorbance and thermal conductivity of nanofluids were measured by UV/VIS Spectrophotometer and Hot Disk thermal property analyzer, respectively. The effects of reaction temperature and PVP addition ratio on the stability and thermal conductivity of nanofluids were analyzed. Results reveal that the thermal conductivity growth rate of the nanofluid increases almost linearly with the increase of the reaction temperature, although the stability decreases slightly, and the effect is not significant. Adding different proportion of surfactants can improve the stability and thermal conductivity of nanofluids effectively, but there is a best proportion. When the reaction temperature is 200℃ and the amount of PVP added is 4 times the sum of the amount-of-substance of Pt and Sn, the thermal conductivity of PtSn nanofluids is greatly improved at the temperature of 60℃, which is about 15.1% higher than that of EG.