Since potassium hexatitanate whisker is often used for the filler of composites or as a catalyst, its surface is very important. In this paper the surface morphology and structure of potassium hexatitanate fiber has been observed by AFM. The potassium hexatitanate fiber shows that its surface has different "lamellas". In addition, we obtained the temperature dependence of the linear expansive ratios along a, b, c 3 directions of the cell by molecular dynamics simulation. The simulation result shows that the linear expansive ratios along the 3 directions are almost the same. Therefore, the periodical surface structure is not generated by the shrinkage along 3 directions in the cooling process of the K2O.6TiO(2) whisker preparation. The surface structure is believed to be related to the mechanism of crystal growth of the K2O.6TiO(2) whisker and is consistant with the "liquid melt inducing" model [22]. (C) 2003 Kluwer Academic Publishers.