Writing anxiety has been identified as a significant obstacle for English as a Foreign Language (EFL) learners in China, with previous studies indicating that it can negatively affect writing performance. Despite this, most research on writing anxiety in the Chinese EFL context has focused on the relationship between writing anxiety and writing performance, with limited attention paid to exploring writing anxiety during the writing process and its sources in depth. This study applied a qualitative method to explore Chinese EFL learners' writing anxiety in the writing process. Thematic analysis was used for analyzing data collected through semistructured interviews with 18 Chinese EFL learners. The results revealed seven primary themes, including lack of knowledge about the writing topic, inexperience with the genre, challenges with brainstorming or coming up with ideas, trouble with structuring or arranging information, difficulty with integrating sources, linguistic difficulty, and negative or no feedback from instructors. The findings indicated that writing anxiety accompanies throughout the writing process. EFL learners need strategies to alleviate writing anxiety, including clear instructions on how to approach writing tasks, provision of appropriate resources, individualized feedback, and a supportive learning environment.