Bismuth layered oxide Aurivillius compounds (An-1BnO3n+1)2-(Bi2O2)2+ (A =Bi,Sr,Ba,etc.,and B =Ti,Nb,Fe,etc.),which consist of n unit cells of perovskite ABO3 blocks alternated with Bi2O2 bilayers along the crystallographic c axis,have attracted wide interests for their special layered structure and potential applications such as room temperature single-phase multiferroic devices in recent years [1-5].However,the growth of Aurivillius layered oxides thin film in the higher-order numbers is a long-standing challenge due to their thermodynamic phase-instability and the large stacking layer number [6-10].Here,the c-axis Bi6FeCoTi3O18 (BFCTO) epitaxial thin films with uniform n =5 layered structures were fabricated by determining the optimal growth temperature and oxygen pressure within very narrow ranges.On the other hand,we find that by inserting a conducting and lattice matched conductive buffer layer,high quality epitaxial BFCTO thin films can be easier fabricated,in which the atomic-scale sharp interface between the film and the metallic buffer layer explains the enhanced quality.This study is important to control the growth of complicated layered oxide thin films,which opens the door to further understand the underline physics and to develop new devices.