The characteristics and application of three analysis methods connecting with TEM on tiny inclusions,i.e.scattering crystals,replication
and
metallic thin film,were discussed.The result shows that scatter crystals are suit for analyzing the shape and size of inclusions; replication is suit for researching the shape, size, site of inclusions and the relationship between inclusions and microstructure; metallic thin film is suit for investigating the forming of the inclusions, the structure types of mixed inclusions and misorientation between the inclusions and matrix. With the method of replication, the heating temperature of hot rolled slab was deduced by analyzing the size of the precipitates. With the approach of metallic thin film and EDS,it is found that different inclusions had different forming temperatures,and the lower temperature inclusions could be formed and grow on the higher temperature inclusions. By analyzing the deformation of the inclusions after hot rolling,it is determined that the high temperature plastic inclusions were the main reason that decrease the mechanical properties in steel.