Wireless Sensor Network (WSN) should be capable of fulfilling its mission, in a timely manner, in the middle of intrusion, attacks, accidents and failures in hostile environment. However, current security mechanisms for WSN are able to satisfy confidentiality, integrity, and authentication properties using cipher algorithms, key management schemes, and so on, but they are not enough to meet above requirements. Therefore, we propose a framework of survivability model for WSN. Our model adopts software rejuvenation methodology, which is applicable in security field and also less expensive. We model and analyze each cluster of a hierarchical cluster based WSN as a stochastic process based on semi-Markov Process (SMP) and Discrete-Time Markov Chain (DTMC). The model analysis indicates the feasibility of our approach.