Brick samples were prepared through vitrification process with two different kinds of EAF dust. Leaching concentrations of various metal ions and anions for the bricks(20wt% EAF dust-80wt% clay) were evaluated by ICP and IC analysis. The results of leaching test showed that the concentration of ions leached from bricks were proportional to the square root of time and saturated with leaching time. The saturated concentrations of alkali and alkali-earth metal ions were 0.1-250ppm; on the other hand, the heavy metal ions were 0-0.084ppm. The efflorescence mechanism of EAF dust-clay bricks was studied by quantitative analysis for the effects of various metal ions and anions. Efflorescence formed on the brick surfaces which were immersed in DI water and dried slowly in the air were characterized by SEM, EDS and XRD. The results of EDS and XRD showed that the main component of the efflorescence was water soluble Na2SO4 .