This article aims at the feature analysis of four expository essays (Text A/B/C/D) written by secondary school students with a focus on the differences between spoken and written language. Texts C and D are better written compared with the other two (Texts A&B) which are considered more spoken in language using. The language features are discussed mainly in three aspects (which are most salient among the four texts): nominalization, lexical density and grammatical intricacy, and personal pronouns.Through the analysis, the discrepancy between spoken and written language is highlighted. Some relevant pedagogical implications are subsequently drawn and expected to be helpful to those teaching academic writing.