The magnesia-alumina based wet gunning mix was prepared using tabular corundum aggregates, fused magnesia aggregates, tabular corundum micropowder, silica micropowder and pure calcium aluminate cement as the main starting materials. Effects of silica micropowder additions (0, 0.2%, 0.5%, 1.0%, 1.5%, 2.0%, and 2.5%, by mass, the same hereinafter) on properties of the gunning mix were researched. The results show that when the silica micropowder addition is 1.0%-2.0%, the gunning mix has good flowability and pumpability. Adding 2.5% silica micropowder, the nepheline forms at 1 600 ℃, which will reduce the high temperature properties of magnesia-alumina wet gunning mix. The introduction of silica micropowder has obvious effects on cold mechanical properties of the gunning mix. For the specimens dried at 110 ℃, the strength increases slightly with the silica micropowder addition increasing. For the specimens heat-treated at 1 600 ℃ for 3 h, the strength increases markedly with the silica micropowder addition increasing. When keeping the water addition and particle size distribution constant, the residual linear expansion rate of the specimen with 1.5% of silica micropowder is the lowest. Hot modulus of rupture at 1 450 ℃ for 0.5 h of the specimens decreases gradually with the increase of silica fume addition. A small amount of silica micropowder is beneficial for the slag penetration resistance.