Abstract: In the smart grid, the existing aggregation schemes often ignore the problem that the smart meter fails and the control center cannot decrypt the aggregated ciphertext, resulting in the failure of the system. Based on EC-ElGamal algorithm, an efficient and fault-tolerant data aggregation scheme in smart grid is proposed. The joint decryption between the trusted third party and the control center could not only achieve fault tolerance, but also resist various attacks. The scheme reduced the computing and communication overhead of the system, improved the practicability of the system, and was easier to deploy in practice. Security analysis and function analysis show that the proposed scheme has good security, fault tolerance and flexibility.