The physical characteristics of mortar specimens made of cement:sand:water=1:3:0.5 and subjected to hydrochloric acid attack were investigated by means of the accelerated corrosion test. The variations of the longitudinal wave velocity of mortar specimens and the alternations of the concentration of hydrion and calcium ion in hydrochloric acid solution were inspected. The results show that the characteristic of chemical reactive stage is found; and the delayed action of the dissolved out Ca2+ is observed; then the scale effect of different specimens is analysed.