The reachable set estimation and stabilization problems of large-scale switched systems have been investigated in this paper. To start with, a class of specific Lyapunov functions for the reachable set estimation of large-scale switched systems is proposed. Secondly, by the method of the proposed specific Lyapunov functions of the large-scale switched systems, the boundary of system state response is calculated under arbitrary switching, which might be used for the safety verification. Then, the concept of decentralized control is introduced and the decentralized state feedback controllers are developed to ensure the state trajectories of the closed-loop large-scale switched systems are limited within the estimated set and guarantee the system globally uniformly asymptotically stable. Finally, several numerical and practical examples are established to confirm the effectiveness and correctness of our results.