The invention discloses an efficient and reliable anomaly detection method for MMORPGs. The method comprises the steps of 1, mapping a player event to a ''player ID-timestamp-operation ID-parameter'' four-dimensional space by means of a tetrad, aggregating the full-scale events of all players, splitting a player sequence into rank sequences with upgrading as the time point for splitting, and conducting operation frequency statistics on the rank sequences; 2, conducting event frequency extraction on all users based on the same rank, and conducting normalization on each event frequency; 3, taking operation union sets of all players according to rank, and conducting equal-length extension on the operation of each player to obtain a numeric type vector; and 4, conducting column-based clustering, conducting dimensionality reduction on k events with the best clustering effect, conducting secondary clustering, dividing players into a plug-in cluster and multiple normal clusters, and conducting clustering on the clusters with the highest recall rate, so that detection is achieved. Corresponding detection devices include a log discretization module, a MeanShift module, a normalization module, a dimensionality reduction module, a primary clustering module and modules before the primary clustering module. The efficient and reliable anomaly detection method for MMORPGs is used for plug-in detection of MMORPGs.