A new evolving network model based on complex network theory among the cluster heads is proposed to study the influence of node failure on the performance of wireless sensor network. According to the proposed model, we discuss the virus immunization strategies, and present a new immune mechanism. Theoretical analysis shows that such an evolving network not only has strong fault tolerance, but also can effectively avoid node premature death caused by the rapid energy depletion. It is also found that if the global network information is unknown, the proposed immunization strategies in this paper can obtain better immune effect than the random immunization and acquaintance immunization strategies. The theoretical analysis is verified by numerical simulations.