AFOP-10（anionic-nonionic emulsified viscosity reducer）was synthesized from bisphenol AF(BPAF), p-hydroxybenzenesulfonic acid(PHSA), and polyoxyethylene octyl phenol ether-10(OP-10). The surface properties, the temperature resistance and salt tolerance performance was tested. The structure-function relationship was studied, and the mechanism of the emulsified viscosity reducer was preliminarily explored. The results showed that the HLB of AFOP-10 was 11.37, the turbidity point(Tk) was 75℃, the critical micelle concentration（cmc）was 0.08 g/L, and the surface tension of AFOP-10 was 30.30 mN/m. AFOP-10 showed good surface activity. The thermal degradation temperature of AFOP-10 was 363℃. The maximum salt-tolerant concentration of the emulsified viscosity reducer was 49476 mg/L with the molar ratio of BPAF, PHSA and OP-10 1∶6∶9. In the simulated brine system with salinity of 8246 mg/L, AFOP-10 still had good activity after aged at 300℃ for 24 h. The viscosity reduction rate could reach more than 98.50%. AFOP-10 had good emulsification and viscosity reduction effect on oils in different areas of Bohai Oilfield, and it had good universality.