The distinction between near‐synonyms has always been a difficult task for English learners in China. Based on Corpus of Contemporary American English (COCA), this article provides a comprehensive description of the similarities and differences between a pair of English synonyms "reduce" and "diminish" in terms of word frequency, collocation, colligation and semantic prosody, in order to support and help English learners to better grasp the usage of these two synonyms, and thus provide a reference for vocabulary teaching and second language acquisition (SLA). The results show that the two synonymous verbs reduce and diminish show some differences in terms of word frequency, collocation, colligation and semantic prosody. Secondly, the two verbs are more often used in academic domains and formal discourse, and they are often combined with nouns, especially abstract nouns. In addition, reduce is frequently used with negative abstract nouns, while diminish with positive abstract nouns.