Abstract: U(Ⅳ) is the reductive agent of plutonium stripping unit(1B). The simulation of single-stage of 1B was studied in this paper. A new model and algorithm on reductive stripping of Pu(Ⅳ) with U(Ⅳ) from 30%TBP/OK was proposed, based on the iterative model. A computer program for simulating the single stage was developed. The data obtained from literature were compared with the model calculated data. In general, the experimental results seem to agree with the model, and the reliability and accuracy of the model proposed are better than the literature model.