The Cu-vermiculite, with 5.5% copper (equal to 80% CEC of vermiculite) and excellent antibacterial performance, was obtained by ion exchange method based on its specialty in cation exchange. On the basis of XRD, TEM and EDS analyses combined with calculation of crystalline parameters and crystal formula, the structure character of Cu-vermiculite was investigated. The similar atom radii and electrovalences of Cu2 and Mg2 suggest that the XRD character of Cu-vermiculite are close to that of standard Mg-vermiculite. A part of Cu2 occupied the interlayer cation sites in the form of hydrate in vermiculite, whereas others turned into octahedral coordinate positions to replace Mg2 . The values of a0 and b0 of the Cu-vermiculite crystal cell had no obvious change compared with that of vermiculite micropowder, but the c0 value slightly decreased, which is desirable for the stabilization of the Cu2 in Cu-vermiculite.