A power grid anomaly rapid detecting and positioning method based on principal component analysis is provided. The method is characterized by subjecting a power grid random matrix to dimensionality reduction, extracting a principal component, determining power grid anomaly according to the strength of the principal component, and positioning anomaly according to the position of an abnormal point. The method achieves anomaly detection and anomaly positioning of the power grid by using the principal component analysis, provides information support for subsequent processing and elimination, and has obvious advantages when processing large-scale data.