The organic modification of nano-scale TiO2 and the effect factors were studied by using dodecanoic acid and hexadecanoic acid as modifier.The results showed that the optimal modification time was 1.5h and the optimal temperature was 100℃.The surfaces of TiO2 particles were modified from hydrophilic to hydrophobic.The modification effect of hexadecanoic acid was better than that of dodecanoic acid.