Abstract: In light of the fact that traditional rock classifications for mined tunnels have difficulty meeting the construction requirements for a tunnel excavated by rotary drum cutter (RDC), it is necessary to set up a rock classification system for tunnels excavated by RDC and to understand the influences on RDC excavation. Using the RDC excavation of the Zhaojiawan tunnel as an example, a rock classification is proposed for the RDC excavated tunnel by considering tunnel stability and construction efficiency based on an analysis of the adaptability of the stratum. To be specific, based on characteristics of different surrounding rocks and the normal and secondary excavation velocities,the rock conditions are divided into 5 grades, i.e., A (good), B(fair), C (poor), D (very poor) and E (unsuited for RDC excavation).