The invention discloses a sustainable user identity authentication method and system based on electromagnetic radiation, which comprises two parts of SVM classification model training and sustainableidentity authentication. The SVM classification model training mainly comprises training the SVM classification model according to electromagnetic radiation signals of each user power adapter and saving. The sustainable identity authentication mainly comprises the sustainable identity authentication of the user by using the SVM classification model and the electromagnetic radiation signal of the current power adapter of the user terminal. The invention combines the elliptic curve cryptography public key encryption and the support vector machine technology to complete the sustainable authentication of the user identity by utilizing the electromagnetic radiation signal of the power adapter, and has the advantages of high accuracy, high security and good user experience.