Abstract: Strain hardening cement-based composite (SHCC) owning to its advantages of high ductility and controllable crack width has been widely used in the strengthening and repairing of concrete structures exposed to severe marine corrosion zones. Based on this, a convection-diffusion model of chloride transport in SHCC subjected to marine drying-wetting cycles was proposed, and a two-dimensional mesoscopic model considering the chaotic distribution of fibers was established by COMSOL simulation software. The spatial and temporal distribution of chloride content under different drying-wetting ratios (3.0∶1, 11.0∶1 and 85.4∶1) and exposure durations (30 days, 90 days and 180 days) was analyzed by conducting a simulated indoor test of chloride ingress into SHCC. The effectiveness of the mesoscopic numerical model to simulate chloride ingress behavior was contrastively verified. The results show that the peak chloride concentration inside SHCC increases with the extension of exposure time, and similarly increases with the increase of drying-wetting ratio. However, with the increase of penetration depth, the chloride concentration rapidly decreases and tends to be stable eventually, which make the chloride content as a whole show a higher peak concentration and a smaller penetration depth. According to the analytical solution to Fick's second law and considering the effect of convection zone, both the surface chloride concentration (C_s) and apparent chloride diffusion coefficient (D_app) of SHCC show obvious time-varying characteristics. At a given drying-wetting cycle ratio, the C_s and D_app increase and decrease as the exposure time increases, respectively. When the drying-wetting cycle ratio is 85.4∶1, compared to 30 days, the C_s of SHCC for exposure to 90 days and 180 days increase by 51.72% and 83.45%, and the D_app decreases by 27.71% and 48.50%, respectively. At the same exposure time, as the drying-wetting cycle ratio increases, both the C_s and D_app first increase and then decrease. Finally, the comparison between the measured data and calculated results of the chloride content distribution indicates the feasibility of the proposed convection-diffusion model under the cyclic drying-wetting action to depict the chloride transport behavior in SHCC.