1. A complex event evaluation system, comprising: an event aggregation module receiving a plurality of first events, each comprising at least one event value, and generating an event pool comprising at least one second event according to the first events; a weight calculation model comprising a weight calculation function corresponding to the at least one second event, where the weight calculation function comprises weightings corresponding to respective first events; and a weight score calculation module calculating a weight score of the at least one second event according to the event values corresponding to respective first events and the weight calculation function corresponding to the at least one second event, evaluating a critical level of the at least one second event according to the weight score of the at least one second event retrieving the weight scores of the historic events of the at least one second events from the event history database, normalizing the weight score of the at least one second event accordingly to obtain a normalized weight score of the at least one second event, and comparing the normalized weight score with at least one predefined threshold to obtain the critical level of the at least one second event.