By uniaxial tensile and compressive tests， the effects of BaCl₂ on the mechanical properties of high ductile alkali-activated slag-based composite （HDASC） were investigated. The results indicate that the addition of BaCl₂ with 3.0% content makes the setting time prolongate to 109 min. The increase in BaCl₂ content leads to gradual decrease in the initial cracking strength， tensile strength and compressive strength， especially the addition of 3.0% BaCl₂ corresponds to a 50.0% decrease ratio， nevertheless， the tensile strain almost maintains the range between 6.24%-9.66%. The microscopic testing results show that the addition of BaCl₂ incurs the decrease of hydration reaction degree of HDASC and the increase of pore numbers， thereby reducing the compactness of matrix and weakening the bonding between fibers and matrix.