this paper, a novel heuristic event filtering methodology that exploits the temporal characteristics in the Complex Event query is presented. Complex Event query is processed in Complex Event Processing(CEP). CEP involves inferring complex events from primitive events in real time. Massive amount of primitive events arrive in real time from multiple distributed sources in real time applications like E-business applications, Business Intelligence systems, Stock Monitoring Systems and Hazard Monitoring Systems. Removal of irrelevant events or filtering will result in effective processing. Thus, there is a need for effective filtering mechanism to filter out the irrelevant events. Therefore, Event Filtering (EF) is to be performed ahead of the event processing. A heuristic event filtering methodology over Sliding Window to increase the throughput of the system is proposed. The proposed system has been validated using a prototype.