<p>Investigation on swelling properties of compacted bentonite with consideration of heating and salinity effects is of great significance for design and safe operation of deep geological repositories for disposal of high-level radioactive waste (HLW). In this study, one-dimensional deformation tests were performed on compacted GMZ bentonite specimens with infiltration of NaCl and CaCl₂ solutions at different temperatures. Thermal and saline effects on the swelling deformation properties were investigated. Meanwhile, MIP tests were performed to quantitatively find out evolutions of the pore size during solution infiltration at temperatures. Results indicate that in the primary stage, the swelling process was accelerated by increasing temperature and solution concentrations. In the final swelling stage, the combined effect of temperature and salinity greatly reduced the swelling strain. MIP results revealed that the total void ratio (<i>e</i>_t) and macropore void ratio (<i>e</i>_macro) decreased with increasing temperature and concentration, while the mesopore void ratio (<i>e</i>_meso) and inaccessible pore void ratio (<i>e</i>_i) slightly changed. This indicated that the decrease in swelling capacity could be related to the disappearance of macropores due to the increase in temperature and salinity. High temperature decreased the basal spacing of montmorillonite and reduced interlayer hydration; moreover, the salt concentration slowed down the diffuse double-layer swelling, resulting in a decrease in macropores and the reduction of swelling capacity of compacted bentonite. Finally, an equation was developed and verified for describing void ratio evolutions with consideration of temperature and concentration effects.</p>