Polymer flooding agents commonly used in oilfields have high consumption and poor salt resistance and tend to undergo chromatographic separation when compounded with surfactants. In view of these problems，the carboxyl nanofiber strips of the natural polymeric compound were selected as raw materials，and single-component flooding agents of hydrophobically modified nanofiber strips（CCNF-n）and amphoteric-hydrophobically modified nanofiber strips （ACCNF-n）were prepared for heavy oil. The effects of the hydrophobic modification degree and amphoteric-hydrophobic modification on the interfacial activity，emulsification ability，and oil displacement performance of carboxyl nanofiber strips were evaluated. The results showed that the increament of hydrophobic modification degree first increased and then decreased the interfacial activity of carboxyl nanofiber strips，and the interaction between the carboxyl nanofiber strips and the water was enhanced due to the introduction of cationic groups，which made the interfacial activity of amphoteric-hydrophobically modified nanofiber strips with the same hydrophobic modification degree decrease correspondingly.Under the conditions of 70 ℃ ，salinity of 50 000 mg/L，and mass fraction of 0.2%，the nanofiber strips with a greater hydrophobic modification degree indicates a higher viscosity. The viscosities of five hydrophobically modified nanofiber strips ranged from 1.54 to 3.85 mPa·s. Under the same conditions，the viscosities of the amphoteric-hydrophobically modified nanofiber strips fluctuated between 18.46 mPa·s and 27.31 mPa·s，exhibiting excellent salt resistance.The results of core displacement experiments showed that the amphoteric-hydrophobically modified nanofiber strip system could significantly enhance the oil recovery（18.91%）.