The effect of redispersible emulsion powder on the fluidity, compressive strength, flexural strength, tensile bond strength and flexibility of steel slag mortar was investigated. The test results show that flexibility and tensile bond strength of steel slag mortar increase, compressive strength reduces greatly and flexural strength reduces at early age but increases at 28 d with increase of use level of redispersible emulsion powder. In addition, flexibility of steel slag mortar improves a lot with the addition of redispersible emulsion powder. A certain amount of redispersible emulsion powder can be incorporated in steel slag mortar to greatly increase tensile bond strength, enhance flexural strength and improve flexibility.