With the progress of wireless sensor network (WSN), this emerging technique is soon applied in many industrial projects. However, a standard to describe the security level in WSN is still lacking, which becomes very needful today. In MoSe Project we try to build a formal model to describe the security level of sensor network and also to give guideline of how to achieve these security levels. The work comprises following parts: collection of academic and industrial applications of WSN; building a formal characteristic card for WSN; investigating a formal model of security-related issues and the risk analysis with real examples.