A layered and distributed dual-bus communication scheme is presented and designed， which is point-to-point based and organized according to functions. The mirror and bus load balancing techniques are introduced into the scheme to make it flexibly and efficiently realize the distributed automation function and the local information integration function， eliminating the effects of the layered scheme on the communication speed and reliability. The reliability of the proposed scheme is quantitatively analyzed. The scheme is being successfully applied in some substation automation systems.