Abstract: The microstructure of the wrought 14Ni3CrMoV steel after normalizing and tempering treatment has been investigated by transmision electron microscopy(TEM). The results show that the predominant bainitic microstructure, formed in the normalizing process, has changed distinctly after high temperature tempering. There are abundant carbides precipitated, distributing homogeneously in the matrix. Most of these carbides are arranged orderly, orienting the direction of the original lath bainitic ferrite. A constituent of ferrite and carbide exists in some region and the block residual austenite which is dominant in the normalized state is not found after tempering.