In a Pub/Sub system, the procedure of distributed event detection can be divided into two interacting phases: the subscription matching and the subscription/event routing. Also, the performance of the system is greatly influenced by these two parts. Adopting a reuse strategy in matching and routing can reduce matching workload and network traffic. However, few of the existing researches provide a reuse solution comprehensively in distributed environments. This paper focuses on exploiting reuse to improve distributed complex event detection. The Pub/Sub system OGENS is introduced, in which the reuses are exploited in the channel-based subscription/event routing and the complex event matching.