Abstract: Based on multi-factor mixture experimental designs,Al₂O₃-CaO-CaF₂ system agglomerative fluxes with high toughness were investigated,and the thermal expansion coefficients of slag were determined.The complex interaction regularity among seven components in agglomerative flux on the thermal expansion coefficients of slag was studied.The relation between thermal expansion coefficients of slag and detachability was discussed and the quantatatine regression equation of thermal expansion coefficient with flux components was developed.Results showed that the addition of ZrO₂ has a significant effect on the thermal expansion coefficients of slag.When ZrO₂10%,thermal expansion coefficients increase gradually with the addition of ZrO₂,but the mutual action of a small amount of ZrO₂ with MgO-CaF₂ can cause a decrease in thermal expansion coefficient.Furthermore,the ratio of MgO/CaF₂ is important to control the thermal expansion coefficients of slag,when it is close to 1,the thermal expansion coefficient decreases greatly.