Abstract: In order to investigate the effect of surfactants on the flow boiling heat transfer of nanofluids refrigerant Al2O3/R141b in microchannels, two-step process was used to prepare 0.2wt%SDBS, 0.3wt%SDBS, 0.3wt%CTAB, 0.4wt%CTAB, 0.1wt%Span80, 0.2wt%Span80 modified nano-refrigerant and 0.1wt%Al2O3/R141b pure nano- refrigerant. The flow boiling and heat transfer experiment of surfactant modified nanometer refrigerant was carried out in a rectangular microchannels with a height of 2.0mm and a width of 1.0mm respectively，and the design system pressure was 170kPa, the heat flux density was 9.4 kW/m2 to 33.5 kW/m2, and the mass flow rate was 219.9 kg/(m2?s)~439.8 kg/(m2?s). The results showed that the surfactant has significant effect on the flow boiling heat transfer coefficient of nano-refrigerant, the average heat transfer coefficient of the nano-refrigerant saturated boiling zone increased by 27.7%, 17.9%, 13.8%, 8.9%, 7.9%, and 5.3% when the surfactant was 0.2wt%SDBS, 0.3wt%SDBS, 0.3wt%CTAB, 0.4wt% CTAB, 0.1wt%Span80 and 0.2wt%Span80, respectively, compared with the pure nano-refrigerant. The smaller the agglomerated particle size of the surfactant-modified nano-refrigerant, the larger the heat transfer coefficient. The surface activity enhancement factor (SEF) increased with the increase of the mass flow rate, and the SEF decreased with the increase of the heat flux density at the same mass flow rate. The anionic surfactant SDBS has the best effect on the fluid boiling heat transfer of nanofluids, the cationic surfactant CTAB is the second, and the nonionic surfactant Span80 is the worst.