In order to study the damaging mechanism of pulmonary alveolar macrophages, the changes of their death ratio,malandialdthyde (MDA) content and activities of dehydrogenate (LDH) and superoxide dismitase (SOD) were determined, and the technique of VITRO cell culture was used to investigate the cytotoxicity of dusts of six minerals (twelve cryst habits) from twelve mineral deposits. The results show that wollastonite and zeolite have no cytotoxicity while dusts of other fibrous and grainy minerals may damage pulmonary alveolar macrophages in various degrees. The cytotoxicity of fibrous mineral dust exceeds that of the grainy one; the cytotoxicity of dust is positively correlated with the active OH- content in dust, but not necessarily so with its SiO2 content; the high pH values produced by dust is unfavorable for the survival of cells; the dust with a low bio-resistance is safe for cells; the content of variable_valency elements may influence cytotoxicity. It is suggested that the shape of mineral dusts is one of the factors affecting cytotoxicity, and that the cytotoxicity of mineral dusts mainly depends on its properties.