In this paper,the influence of set- retarding on applications of alkali- slag cement and concrete is analysed.Set character of alkali- slag cement and suitability of measures used at home and abtord are discussed.On the basis of above mentioned,it is proposed that the only way to solve the fast- set problem of alkali- slag cement is by incorporating efficient retarders,and researches on mechanism of retarders along with deve loping new composite retarders are the most important topics in the research field of alkali- slag cement and concrete.