The invention relates to the field of information security, in particular to a key management, data encryption and identity authentication method oriented to an electrical measuring instrument. The method is remarkably characterized in that an asymmetrical encrypting-decrypting mechanism is adopted, and executed by two independent servers; a main server is used for generating and managing public and private keys; and an auxiliary server is used for decrypting a random number sequence generated by the electrical measuring instrument and transmitting the random number sequence to a monitoring center, so that the security of an incredible or unreliable communication transmission link is enhanced. The robustness of information security guarantee is enhanced through electrical energy instrumentidentity authentication based on an OCSVM (One-Class Support Vector Machine) algorithm, and extra processing overhead does not need to be increased. The method can be implemented with limited storageresources and computation capability of the electrical measuring instrument.