Abstract: Based on the principle of Gibbs free energy minimization, the thermodynamic model of the jamesonite flash smelting multi-phase equilibrium system was built using element potential method. Then, the effects were studied of the oxygen volume per ton concentrate (OVPTC), the oxygen grade (OG) and the smelting temperature (T) on the lead and antimony distribution rate in equilibrium products. Results show that, for the jamesonite concentrate with a certain composition, the lead distribution rate in alloy decreases continuously with the rise of OVPTC but increases slightly with the rise of T; The antimony distribution rate in alloy decreases slightly with the rise of OVPTC but increases markedly with the rise of T; The smelting gas quantity reduces dramatically with increasing OG. Therefore, taking into account the recovery rate of lead and antimony, for the jamesonite flash smelting process, OVPTC should be suitable low, OG and T should be relatively high.