Abstract: The separation characteristics of H₂/HT/T₂ system with side stream were investigated by a theoretical calculation. The dynamic behavior of composition concentration in reboiler and condenser was obtained as well as distribution along distillation column. The effects of reflux ratio and operating pressure on separation performance were also studied. As pressure increases from 0.06 MPa to 0.12 MPa, detritiation efficiency η drops to 81%, and a 2 K temperature increase on distillation column is observed. Reflux ratio has remarkable influence on η, and η exceeds 99% as reflux ratio is greater than 5.