Abstract: With the rapid development of smart grid communication technology, frequent data transmission brings a series of security risks. 1) Transmitted data is easy to be stolen by different attacks (Man-in-the-middle attack, DoS attack et al.) , which may bring data leakage; 2) Most existing schemes depend on the trusted third party which is honest but curious. Attackers may execute privileged insider attack to steal secret parameters; 3) Keys stored in smart meters may be stolen. A lightweight authentication and key agreement scheme based on elliptic curve cryptography (ECC) in smart grid is proposed in this paper. ECC was used to ensure efficient authentication. At the same time, the proposed scheme does not need to depend on a third party. The Real-or-Random (RoR) Model was used to conduct formal security analysis on the proposed scheme. The experiments demonstrate that the proposed scheme is more efficient compared with other existing schemes.