The necessity to secure the communication between wireless sensor networks nodes becomes important with the system nodes are being deployed for a wide variety of applications. In this paper, we propose a new approach for session key management among group sensor nodes. We use initial trust node to build a small set of shared keys, low-cost protocols enable neighboring sensors to authenticate and establish secure local links. Each shared key used only once after the set of shared keys are built. Our session scheme exhibits a nice power efficient and excellent updating communications keys. At the same time our scheme updating keys go with exchanging message. Extensive analyses and simulations are conducted to evaluate the proposed schemes, and the results show that the proposed management schemes can achieve a good level of security.