The product of syngas mainly came from 〈CaSO4 + 4C → CaS + 4CO〉 solid-solid reaction and 〈C + H2O(g) → CO + H2〉 gas-solid reaction. Lower heating value (LHV) and cold gas efficiency were higher than 55000.00 kJ/Nm3 and 63.00%, respectively. Optimizing operation conditions were obtained using Factsage 6.4. Theory and experiment showed that PG is an excellent oxygen carrier for syngas production during lignite’s IG-CLC process.