In this paper, two kinds of long-chain amine oxide surfactants, erucamidopropyl dimethylamine oxide (EAOS) and oleamidopropyl dimethylamine oxide (OAOS) were synthesized and compounded with different mass ratios. The rheological tests show that there is a synergistic effect between EAOS and OAOS, and this effect reaches the strongest at the EAOS/OAOS solution with α = 0.7 (α is the mass fraction of EAOS in the mixed surfactant). Through the synergistic effect between EAOS and OAOS, the temperature resistance of amine oxide surfactant solutions can be effectively improved. EAOS/OAOS (α = 0.7) solutions with total surfactant mass fractions of 3, 4, and 5 wt% show good high-temperature resistance at 130, 140, and 150 C, respectively. After shearing for 60 min at 100 s À1 , 160 C, the remaining viscosity of the 5 wt% EAOS/OAOS (α = 0.7) with 1 wt% KCl solution is 30 mPa s, meeting the demand of viscoelastic surfactant fracturing fluids.