Aiming at the problems of high quantity liquid production rate，high oil content sewage and short processing time on Zhaodong platform，the 3rd generation polyamide-amine hyperbranched polymer was prepared with diethylenetriamine and methyl acrylate as raw materials，and then reacted with dimethylamine and epichlorohydrin to obtain dendritic polyamide-amine polycation product KYOR. The branching degree effect of KYOR on oil removal rate and the compatibility of KYOR and demulsifier DGF-18B were studied. Finally，KYOR was applied in the field on Zhaodong platform by continuous injection. The results showed that in the spherical structure of hyperbranched polyamines，the termination and modification with quaternary ammonium salts could improve their hydrophilicity and molecular weight. Among the KYOR series products，KYOR-3 prepared by 3.0-generation polyamide-amine with the highest branching degree had the best oil removal effect. The new oil removing agent could reduce the oil content from 202.8 to 17.8 mg/L and the oil removal rate was high up to 91.22% in 20 minutes when the dosage of KYOR-3 was 30mg/L. Good compatibility was found between KYOR-3 and DGF-18B used on Zhaodong platform，which indicated that there was no effect on crude oil dehydration. The oil content，suspended matter and median particle diameter of injection water were all decreased after KYOR-3 was used in Zhaodong platform，which achieved the index requirements of reinjection water in Zhaodong platform