The particularity of low speed and heavy load rolling loadcase makes the elastic deformation of radial journal bearing in rolling mill far more than that of bearing under general loadcase. Instead of deformation matrix algorithm based on conventional Hertz contact theory, 3D boundary element method (BEM) is used to exactly calculate elastic deformation between contact bodies, the sample is given to calculate the elastic deformation of radial journal bearing in rolling mill. The deformation field and stress field of contact surfaces between bearing and roll are analyzed, as well as the influence of elastic deformation on lubrication properties of bearing.