  We study the normal bundles of the exceptional sets of isolated simple small
singularities in the higher dimension when the Picard group of the exceptional
set is $\mathbb{Z}$ and the normal bundle of it has some good filtration. In
particular, for the exceptional set is a projective space with the split normal
bundle, we generalized Nakayama and Ando's results to higher dimension.
Moreover, we also generalize Laufer's results of rationality and embedding
dimension to higher dimension.
