Three different castables were prepared as steel-ladle purging-plug refractory materials: corundum-based low-cement castable(C-LCC),corundum–spinel-based low-cement castable(C-S-LCC),and no-cement corundum–spinel castable(C-S-NCC)(hydratable alumina ρ-Al_2O_3 bonded). The properties of these castables were characterized with regard to water demand/flow ability,cold crushing strength(CCS),cold modulus of rupture(CMo R),permanent linear change(PLC),apparent porosity,and hot modulus of rupture(HMo R). The results show the CCS/CMo R and HMo R of C-LCC and C-S-LCC are greater than those of the castable C-S-NCC. According to the microstructure analysis,the sintering effect and the bonding type of the matrix material differ among the three castables. The calcium hexaluminate(CA_6) phase in the matrix of C-LCC enhances the cold and hot mechanical strengths. In the case of C-S-LCC,the CA_6 and 2Ca O·2Mg O·14Al_2O_3(C_2M_2A_(14)) ternary phases generated from the matrix can greatly increase the cold and hot mechanical strengths. In the case of the no-cement castable,sintering becomes difficult,resulting in a lower mechanical strength. Three different castables were prepared as steel-ladle purging-plug refractory materials: corundum-based low-cement castable (C-LCC), corundum-spinel-based low- cement castable (CS-LCC), and no-cement corundum-spinel castable (CS-NCC) (hydratable alumina ρ-Al_2O_3 bonded). The properties of these castables were characterized with regard to water demand / flow ability, cold crushing strength (CCS), cold modulus of rupture (CMo R), permanent linear change (PLC), apparent porosity, and hot modulus of rupture (HMo R). The results show the CCS / CMo R and HMo R of C-LCC and CS-LCC are greater than those of the castable CS-NCC. According to the microstructure analysis, the sintering effect and the bonding type of the matrix material differ among the three castables. The calcium hexaluminate (CA_6) phase in the matrix of C-LCC enhances the cold and hot mechanical strengths. In the case of CS-LCC, the CA_6 and 2Ca O · 2Mg O · 14Al_2O_3 (C_2M_2A_ (14)) ternary phases generated from the matrix can greatly increa se the cold and hot mechanical strengths. In the case of the no-cement castable, diseases becomes difficult, resulting in a lower mechanical strength.