This study evaluated the effect of a combined feedback activity (peer feedback, computer-generated feedback and teacher feedback) on students' second language (L2) writing feedback literacy. One hundred and eighty-two Chinese university students participated in this research. Findings revealed that the intervention significantly improved students' literacy in "Appreciating Feedback," "Acknowledging Different Feedback Sources" and "Managing Affect," but not "Making Judgements" and "Taking Action." L2 proficiency levels affected the literacy development. Low-proficiency students' feedback literacy did not change significantly. Middle-proficiency students improved significantly in "Appreciating Feedback," "Acknowledging Different Feedback Sources," "Managing Affect," and "Taking Action." High-proficiency students only improved significantly in "Appreciating Feedback." Findings further reveal different degrees of difficulty for students to improve feedback literacy along its five dimensions. This study bears implications for developing students' feedback literacy in L2 writing and in other disciplinary areas, particularly regarding how teachers could use multiple feedback sources and address students' varied proficiency levels.