Abstract: The extraction of actinides with DHDECMP/TBP/OK from nitric acid and simulated HLLW from reprocessing of power reactor spent fuel is studied. The distribution ratios of Np(Ⅴ), Pu(Ⅳ) and Am(Ⅲ) are studied as a function of a number of parameters such as concentration of nitric acid, salting out agent in aqueous phase and temperature. The distribution ratios of Np, Pu and Am in simulated HLLW are determined, the extraction reaction enthalpy changes, Δ H (Np(Ⅴ)), Δ H (Pu(Ⅳ)) and Δ H (Am(Ⅲ)) are found, and the principle flowsheet of recovering actinides and rare earth elements from HLLW is recommended.