This paper for the first time discusses the relations of the configuration, surface structure and surface properties of chrysotile asbestos with bio_activity based on nanometer-sized material and nanostructure effect. Chrysotile asbestos is a kind of special mineral occurring naturally as one-dimensional nanometer-sized silk. It has the general properties of nanometer-sized material in configuration, structure and surface properties, which are chiefly marked by the configuration of one-dimensional nanometer-sized silk, tubular structure and high activity behavior of the surface (interface). And its bioactivity is formed by the very small size and very high surface activity of fibers. The injuries done by chrysotile asbestos fibers to creatures include not only those of general fibers but also those of the amorphous SiO2 phase. The bioactivity of asbestos fibers increases greatly due to the nanometer-sized effect and the high surface activity of asbestos fibers.