The proliferation behavior of the person's liver cell under actions of the nanoTiO2has been looked into by 3-(4,5-dimethylthiazol 2-yl)-2,5 diphenyltetrazolium bromide (MTT) colorimetric method of Mosmann. In this case we first give some elementary properties of the nanoTiO2and do further the liver cell cultures, and add the nano TiO2into the cells. In accordance with biological rules we measure the proliferation state of the liver cell in normal condition. The result obtained show that the influence of the nanoTiO2on the proliferation of the person's liver cell is very small, when compared with that of the control group. We found further out the size of the toxicity of the nanoTiO2to the chick embryo fibroblast (CEF) cells by the MTT colorimetric method. Thus we determine the toxicity for the TiO2s of 100nm and of 1000nm by the toxicology which are all first score (or degree).