Pyrophyllite was the cheap, environmentally friendly alumina silicate clay minerals. This paper studied optimization of conditions for extraction of acid-soluble Al2O3 from pyrophyllite. Qualitative tests had been performed in studying pyrophyllite crystal at different temperatures by using scanning electron microscopy. Dissolution experiments showed that after thermal activation the behavior of alumina in acid the dissolution was different, which was affected by hydrochloric acid concentration, heat activation temperature and acid leaching time. When the calcinations temperature was 700 °C and hydrochloric acid concentration was 25%, the dissolution amount of alumina largest. The fit results indicated that the research for the relationship between dissolution and time by Using Exponential function series Asymptotic1 model to fitting match was the best. So the above function could be used to estimate each time the dissolution of alumina from pyrophyllite in hydrochloric acid.