In this paper, a novel packet classification scheme optimized for multi-core network processors is proposed. The algorithm, Explicit Cuttings (ExpCuts), adopts a hierarchical space aggregation technique to significantly reduce the memory usage. Consequently, without burst of memory usages, the time-consuming linear search in the conventional decision-tree based packet classification algorithms is eliminated, and an explicit worst-case search time is achieved. To evaluate the performance of ExpCuts, we implement the algorithm, as well as HiCuts and HSM, on the Intel IXP2850 network processor. Experimental results show that ExpCuts outperforms the existing best-known algorithms in terms of memory usage and classification speed.