Identity authentication is critical to the security of wireless sensor networks（WSNs）.An identity authentication scheme for clustered WSNs based on elliptic curve cryptosystem（ECC） is proposed.The scheme presents a stratified strategy that the nodes with strong computing ability are responsible for the public key based complex calculations

and the nodes with weak computing ability are responsible for the symmetric key based simple calculations.The analysis shows that

compared with traditional authentication schemes

the proposed scheme has superiority in both security and efficiency.