In this research, The quaternary ammonium salt ionic liquid Tricaprylylmethylammonium ([A336]Cl) was used as the precursor, Functionalized ionic liquid [Tricaprylylmethylammonium][di-2-ethylhexylphosphinate]([A336][DEHP]) was synthesized by ions-exchange process. Its structure was characterized and analyzed by ATR and NMR. Using [A336][DEHP] as extractant, Trioctylphosphine oxide(TOPO) is a synergistic extractant. Extraction and separation of Nd(Ⅲ) in chloride medium using [A336][DEHP], [A336]Cl+TOPO, [A336][DEHP]+TOPO as an Extraction system. The results showed that [A336][DEHP]+TOPO extraction system had better synergistic extraction effect. The results indicated that extraction efficiency of Nd(Ⅲ) increased with the increase in pH, the concentration of salting-out agent NaCl; When the concentration of NaCl was 0.5 mol/L, the pH was 5.0 and the temperature was 25℃, the extraction effect of each extraction system was 85.6%, 78.6% and 96.5%, respectively. ΔH<0, the synergistic extraction appeared to be an exothermic reaction, lowering the temperature facilitates the extraction process; The extraction mechanism is ion association mechanism. Anion and ion do not exchange in the aqueous phase, is an environmentally friendly extraction system. When the mass fraction of HCl arrives at 5%, the loaded Nd(Ⅲ) in organic phase can be fully stripped. After five cycles, the extraction results were still good.