A multi-phase， multi-component ionic transport model was developed in a meso-micro scale， in which the porosity of alkali-activated fly ash/slag（AAFS） concrete， chloride binding effect and electrochemical coupling between multi-species were comprehensively taken into consideration. The reliability of the proposed model was verified by third-party experiments. Based on the proposed model， the effects of fly ash/slag ratio and activator modulus on chloride erosion resistance of AAFS concrete were numerically estimated. The results show that a lower fly ash/slag ratio can significantly improve the chloride erosion resistance of AAFS concrete due to its greater contribution to reduce the porosity. AAFS concrete with an activator modulus of 1.00 exhibits the best resistance to chloride erosion， and a too low or too high activator modulus will increase the penetration depth of chloride ions in concrete.