At present the digital library has entered into the period of cloud computing. The cloud digital library is a kind of virtual library, which is built upon Internet, and uses the cloud computing technology to provide services for readers. For the status and developing trend of cloud digital libraries, a regional cloud digital library network based on the mobile ad hoc network is proposed, the network architecture is designed, and its performance is evaluated by network simulation software NS-2. The result shows that the performance of the network is good, and it is feasible. The research result in the paper is valuable for the study and application of cloud digital libraries.