The effect of the addition of borax on the properties of magnesia-forsterite dry mix was studied by using lightly burned forsterite,sintered magnesia and fused magnesia as raw materials and phenol formaldehyde resin as binder.The results show that borax has little effect on the bulk density of the sample,the strength at room temperature and after burning increases with the addition of borax,and borax can improve the slag resistance of dry materials,but too much of it will have the opposite effect.