The distribution behaviors of iodide complex of Cd (II) in the propyl-alcohol ammonium sulfate aqueous biphasic extraction system was experimentally investigated in this work. Cd (II) was found to be extracted from the propyl-alcohol phase due to its ion pair formation as CdI42-(PrOH2+)2 in the presence of NH4I and in HCL, and the associated extraction conditions were optimized. The experimental results indicated that cadmium can be efficiently extracted by the method, and an extraction rate of 99.1% for cadmium can be achieved under optimizing conditions.