In order to improve the quality of teaching assistants' written corrective feedback in English writing classes, this paper explores the characteristics and types of teacher assistants' written corrective feedback. By analysing the students' manuscripts with feedback provided by teaching assistants, this study finds out that in regard to feedback types, teaching assistants use direct feedback most frequently, followed by metalinguistic feedback, and then indirect feedback. In terms of feedback focus, teaching assistants pay most attention to language form, followed by ideological content and text structure, while pay less attention to the overall quality of writing. With respect to feedback tone, teaching assistants can provide writing feedback with various feedback tones based on students' writing conditions.