Traditional English language teaching approaches, which overlook conceptual differences between Chinese and English, are not very effective for improving idiomaticity of Chinese EFL learners’ English. This paper presents a concept-based approach based on Cognitive Grammar. Starting from difficulties in Chinese EFL learners’ English sentence processing, this approach gives a cognitive account of unidiomatic expressions resulting from conceptual differences between Chinese and English. On the basis of the analysis, the chunks which embody different ways of conceptualization are summarized to help learners develop native-like ways of conceptual processing, and communicative approach is adopted to help learners internalize the conceptual differences.