This paper is devoted to the problem of design a dynamic controller of switched linear systems. In the first part of this paper we give some remarks about the influences of switching signal on the asymptotic stability of switched systems. We give a practical example to generate a large class of switching signals. The second part is devoted to the switched dynamic controller design, based on a common lyapunov function approach. a sufficient conditions are formulated as an LMI problem for the switched controller design under arbitrary switching. A stabilizing switched controller with regional pole placements is also formulated as a convex problem, an LMI approach is used to derive the switched dynamic controller with performance limitations.