Abstract: Take water glass and NaOH as activator, slag powder as cementitious material, calcium oxide and calcium sulphoaluminate expansive agent as admixture to prepare basic mechanical properties specimens of alkali-activated slag concrete(AASC). The basic mechanical properties of cube compressive strength, splitting tensile strength, flexural tensile strength, elastic modulus and Poisson's ratio were studied. The test results showed that AASC had the good early strength performance, SEM microscopic analysis showed that there was no obvious interfacial transition zone between aggregate and slurry interface. Add expansive agent to AASC can improve its early(1d, 3d) strength, and decrease its later (28 d) strength. The tensile toughness of AASC was better than that of ordinary portland concrete with the same strength grade, the flexural strength, elastic modulus and Poisson's ratio were equal to the ordinary portland concrete. Add expansive agent to AASC can greatly reduce the flexural tensile strength of AASC. The result calculated by elastic modulus suggested that the formula mostly close to the experimental value is the Chinese norms.