The invention provides a historical data analysis-based abnormality monitoring method and system of a power distribution network. The method comprises the steps of acquiring historical current data ofa 10KV main line where a power distribution line is located, standardizing the historical current data by taking circuit current limit number as a reference, clustering the historical current data according to a circuit load mode, performing load mode matching on current load data, calculating mismatching degree, judging whether a mismatching degree judgment circuit is abnormal or not, and further determining, pushing and displaying a circuit abnormality type. The method is high in data accuracy and high in reliability and is easy to read and process, so that the constraint that existing power distribution network equipment cannot be used for supporting fault monitoring is got rid of; and moreover, the method is small in data volume, fast in calculation speed and low in calculation equipment requirement, and is easy to promote and implement, existing equipment and data of a power supply enterprise can be fully compatible, and the construction cost is low.