Teaching Chinese as a foreign language is actually the teaching of Chinese as a second language by international Chinese teachers. People must learn vocabulary as a language element in the process of language acquisition. Without vocabulary, there is no language. When we master the vocabulary of a language, we rely on mental lexicon, which is vocabulary that has been stored in the brain for a long time. Through the study of second language mental lexicon, it can be used effectively, and corresponding teaching methods can be used in the vocabulary teaching of Chinese as a foreign language to help students learn Chinese quickly and effectively.