According to the tests for the stability of some mineral fiber dusts in inorganic acid and chemical activity of acid-etched residue, the authors discuss the acid etching process of mineral fiber dusts, especially the changes in surface active groups in the acid etching process, and the factors that affect acid-resistance and chemical activity of mineral fiber dusts. Besides, on the basis of the results of the tests combined with the previous research results of the authors and predecessors, the authors discuss the relationships between the acid-resistance of mineral fiber dusts and the changes of surface active groups in the acid etching process with the bioactivity. The tests indicate that the acid resistance of mineral fiber dusts is related to the crystal structure, crystallinity and quantity of lattice defects, as well as the types and position and exposure degree of the groups. Besides, it is in positive correlation with the specific surface area, properties and number of microholes, and quantity of Lewis acid sites. After acid attack or surface modification, the latent biological toxicity of mineral fiber dusts may be reduced or even disappears totolly.