The invention relates to the technical field of spacecraft abnormal operation state detection, and particularly relates to a cluster analysis-based anomaly detection method which is aimed to solve the technical problem that the conventional spacecraft operation state detection method is difficult to make a state data determination rule and is difficult to determine an abnormal situation of a whole spacecraft. The cluster analysis-based anomaly detection method includes the following steps: determining an optimal cluster distance parameter, performing clustering on historical data, and detecting an abnormal operation state. The method can generate a historical operation state data type model for detection of the abnormal operation state through cluster analysis on spacecraft operation state historical data, and avoid the difficulty of the determination rule made by a man; and the historical operation state data type model for detection of the abnormal operation state can be updated according to current spacecraft operation state data, and an anomaly detection model can be improved according to a current operation condition.