  Three types of thick branes, i.e., Poincar\'{e}, de Sitter and Anti-de Sitter
brane are considered. They are realized as the non-singular solutions of the
Einstein equations with the non-trivial dilatons and the potentials. The scalar
perturbations of these systems are also investigated. We find that the
effective potentials of the master equations of the scalar perturbations are
positive definite and consequently these systems are stable under the small
perturbations.
