Abstract: During the long-term operation of deep geological repository of high-level radiational waste, the chemical environment causes changes to the pore structure of the buffer/backfill material, which can affect the material's hydro-mechanical properties. Under the foundation of fractal theory and dual-porosity theory, we establish two pore structure based SWRC predicting models to study the feasibility of the two theories to connect the microstructure with hydraulic properties of compacted betonite considering chemical effects. The pore size distribution data of compacted GMZ bentonite treated with different concentrations of NaCl solution is obtained by mercury intrusion method. The SWRCs of the samples are predicted through the established models and compared with the measured curves. Results show that the predicted SWRCs tend to be the same as the measured SWRCs in the higher range of matric suction. However, compared with the dual-porosity of the SWRC testing specimen, only the intra-aggregate pores control the water retention capacity of the compacted bentonite after the wetting and drying process. Therefore, the predicted SWRCs show single peak and the established models don't perform well in the lower suction range. Compared with the distilled water treatment, the salt solution leads to the decrease of inter-aggregate porosity and the decrease of water content under the same matric suction. However, with the treatment of more concentrated salt solution, the water retention capacity of the specimen increases slightly in the range of high suction due to the increase of pore fluid channels and the formation of micro-cracks in the compacted bentonite.