This study investigates how Mandarin learners of English use prosody to comprehend focus in English sentences with the focus particle “only” and how L2 proficiency affects their performance. We adopted the paradigm of Ge et al. (2020) and conducted a comprehension experiment on two groups of L2 learners at two levels of English proficiency (advanced: N=36, intermediate: N=30). Participants were presented with question-answer dialogues and were asked to judge whether the answer (with appropriate OR inappropriate prosody) made sense for the question based on a given story as quickly as possible. The results showed that appropriate prosody triggered more “YES” judgements than inappropriate prosody in both groups of L2 learners, regardless of their L2 proficiency. Besides, L2 learners were faster in the appropriate-prosody condition than in the inappropriate-prosody condition in comprehending focus. It seems that Mandarin learners of English match native speakers of English in making use of prosody to interpret focus. Significant differences were observed between two groups of L2 learners: advanced L2 learners gave more “YES” responses and were much faster than intermediate L2 learners with appropriate focus-to-prosody mapping. Our results provide further evidence that L2 proficiency plays a role in L2 comprehension.