Water absorption of porous materials were influenced by sea salt. It would lead to changes of the efficiency of the low-energy buildings using passive evaporation cooling technology. To find the relations between the concentration and the water absorption characters, we conducted water absorption tests through partial immersion method with common porous fire-clay tiles and NaCl solution with different concentrations. Compared to the pure water case, tiles' capillary absorption coefficient was higher by 17.57% in solutions with the concentration of 3.5% by weight (same below), and lower by 12.17% in 26.3% solution. Pure water absorption reduced while concentration increased. Capillary saturated water content was lower in 3.5% solution than in pure water by 2.50%, and lower in 26.3% solution than in pure water by 16.18%. Continuous absorption for 24 hours, the pure water content was lower in 3.5% solution than in pure water by 3.18%, and lower in 26.3% solution than in pure water by 20.51%. In summary, salts would weaken the water absorption ability of the tiles. The higher the concentration of the solution was, the absorption would be weaker. As a result, water absorption of the tiles in the coastal saline environments would be different from the inland situation.