Considering the security authentication requirements due to the massive power terminals in the smart grid scenario, the problem of safe and convenient storage and use of keys in power terminals is studied, and a power terminal security authentication scheme is proposed based on SM9 threshold signature.First of all, the certificateless identity-based cryptographic technology is applied to the power terminal and it can solve the defect that certificate management in the original PKI protection system is relatively complex. Then, the threshold cryptography is introduced to improve the standard SM9 digital signature algorithm.The SM9 private key is split and then stored separately.When using the private key signature, a synthesizing signature is generated via an interactive calculation between the power terminal and the server. Based on this algorithm, a power terminal security authentication scheme is proposed.Finally, an example is analyzed to verify the correctness and security of the scheme.