Abstract: A conceptual design was proposed for heavy water detritiation and upgrading based on LPCE+CD process, and theoretical model was established to study the separation performance with computational program developed under MATLAB platform. About 98.38% of tritium and 98.35% of protium can be transfered from liquid phase to gas phase by LPCE process with 3 for the mole ratio of gas and liquid (r_g/l), and r_g/l has a substantial effect. The enrichment of DT in the reboiler of first cryogenic distillation column is remarkble and reaches almost 30 folds that of feeding tritiated heavy water after 24h. In the condenser of the second cryogenic distillation column, HD is dominant with DT at 10^-11 level. The stripping efficiency for T and H is 99.30% and 97.75% respectively.The consistency between front-end and post-processing can be assured with proper system design, thus HD and DT can be removed simutaneously by LPCE+CD process which is an effective method for heavy water detritiation and upgrading.