Abstract: Standard specimen of uniaxial compression concrete prism and concrete filled stell tube(CFST) specimen were made to investigate the alkali-activated slag concrete(AASC) stress-strain relationship by the testing of uniaxial compression and steel tube constraints conditions. The test results show that the relationship between the cube strength and the prismatic strength can still be expressed by the present standard,and the fitted stress-strain relationship curve with the dimensionless two stage stress-strain relationship model is in good agreement with the test curve under uniaxial compression conditions. The ultimate strength and strain of AASC under steel tube constraints condition are significantly increased than those under uniaxial condition, which indicates that the steel tube confinement can improve the strength and toughness of core concrete, and the fitted stress-strain relationship curve with the stress-strain relationship model of the existing steel tube confined core concrete is in good agreement with the test curve. The results show that the existing stress-strain relation model of ordinary concrete is still applicable to AASC under uniaxial compression and steel tube constraints condition.