Abstract: Non-reactive mould fluxes were designed, and the effects of Li₂O on the crystallization and heat transfer of the fluxes were investigated by using the single hot thermocouple technique (SHTT) and a heat-flux simulator. The results show that increasing the Li₂O content which is less than 2% can weaken the crystallization property of the fluxes. Whereas, when the Li₂O content increases from 2% to 5%, the crystallization temperature, critical cooling rate and crystallization rate constant enhance, but the incubation time of the slag system decreases, indicating that Li₂O improves the crystallization of the fluxes in this range. It is also found that the maximum heat flux density, average heat flux density and characteristic time of the fluxes reduce with the increase of Li₂O content within the range of 2% to 5%.