FactSage thermodynamic software is used to study the material balance of converter fly ash during carbothermal reduction at different temperatures and n(C)/n(O) (molar ratio). The influence rule of roasting temperature, roasting time and n(C)/n(O) on metallization and dezincification rate of converter fly ash is explored by orthogonal test, and the best roasting conditions are obtained. The results show that, based on the thermodynamic principle, when the roasting temperature is equal or greater than 1 200 K, the ZnO in the dust can be completely removed, and the separation of iron and zinc can be realized. In the reduction test, roasting temperature has the greatest influence on metallization and dezincification rate of converter fly ash, followed by roasting time, and n(C)/n(O) in order. According to the principle of minimum carbon distribution, the optimum roasting conditions are obtained when roasting temperature is 1 100 ℃, roasting time is 60 min and n(C)/n(O) is 0.7. Under these conditions, the metallization and dezincification rate of converter fly ash are 99.10% and 98.42%, respectively.