Epitaxial BiFeO(3)thin films with different thicknesses were grown on SrTiO3(001) substrate. The fllm exhibits a structural transformation from "R-like" phase with out-of-plane lattice parameter 4.06 ANGS; to a "T-like" phase with out-of-plane lattice parameter 4.65 ANGS; on increasing the thickness from 16 nm to 60 nm. The parasitic gamma Fe(2)O(3)phase was avoided by using slightly higher oxygen pressure during the growth. The "R-like" phase is shown to exhibit significant magnetic anisotropy and enhanced saturation magnetization which vanishes with the appearance of the "T-like" phase.