Abstract: From the perspective of cognitive poetics, taking the metaphor theory as the theoretical framework and mining and metallurgy novel The Hole Fire as study corpus, the paper tries to explore how metaphors affect the coherence of discourse from two aspects, namely, one metaphor throughout the discourse (the candle representing humanity in the dark ancient tunnels and three extended metaphors about the different aspects of humanity aroused by three different states of candle) and a core metaphor dominating numbers of extended and related metaphors (the other three subordinate images aroused by the center image candle), with a view to widening the field of discourse study and supplying new approaches to the study of mining and metallurgy literature, enriching the understanding toward metaphor and improving our reading and aesthetic ability of Chinese local literature as well.