In order to improve the recovery of the reservoirs with strict conditions，new type of chemical agent was selected，and the effect of hydrophobically associating polymer on the dynamic interfacial tensions of straight and branched chain betaine solutions against kerosene have been studied. The influence of oleic acid in the oil on interfacial tension of betaine systems were investigated. The experiment results show that for both kerosene and model oil containing oleic acid，the mixed adsorption of hydrophobic part of hydrophobic associated polymer and straight chain betaine ASB will lead to the reduction of interfacial tension because the large spaces exist between hydrophobic chains of ASB，which comes from the large size of hydrophilic part in betaine molecule. The compact film will be formed by branched chain betaine BSB because the size of hydrophobic part matches its hydrophilic part. Therefore，the adsorption of hydrophobic part of associated polymer will destroy the tight arrangement of BSB film and result in the obvious increase of the interfacial tension values.