In wireless sensor network,virtual backbone is a cost effective broadcasting method. Connected dominating set formation is proposed to construct a virtual backbone. However,it is NP-Hard to find a minimum connected dominating set in an arbitrary graph. In this paper,based on cross-entropy method,we present a novel backbone formulation algorithm( BFA-CE) in wireless sensor network. In BFA-CE,a maximal independent set is got at first and nodes in the independent set are required to get their action sets. Based on those action sets,a backbone is generated with the cross-entropy method. Simulation results show that our algorithm can effectively reduce the size of backbone network within a reasonable message overhead,and it has lower average node degree. This approach can be potentially used in designing efficient broadcasting strategy or working as a backup routing of wireless sensor network. However, it is NP-Hard to find a minimum connected dominating set in an arbitrary graph. In this paper, based on In BFA-CE, a maximal independent set is got at first and nodes in the independent set are required to get their action sets. Based on those action sets, a backbone is generated with the cross-entropy method. Simulation results show that our algorithm can effectively reduce the size of backbone network within a reasonable message overhead, and it has lower average node degree. used in designing efficient broadcasting strategy or working as a backup routing of wireless sensor network.