Wireless sensor networks（WSNs） are developing rapidly

it will be employed in a wide variety of applications ranging from military

industrial and social.Due to their constraints in computation

memory

and power resources

security is a challenge in these networks.Many security methods of WSNs based on the concept of layered-design have the limit

the state of art security design method of WSNs is overviewed

several new cross-layer solve methods are proposed

and the research direction of cross-layer design for the security of WSNs is point out.