This study explored the self-regulated writing process of EFL learners in the context of China. Drawing upon the writing diaries written by 109 Chinese university EFL learners, the study examined how Chinese EFL learners self-regulated their writing in the pre-, while-, and post- writing phases. The findings showed that the learners went through ten processes (i.e., goal setting, knowledge activation, strategic planning, environmental preparation, organizing ideas and structures, preparing for good mental states, monitoring, controlling, reflection, and reaction) in the three writing phases to self-regulate not only their cognition, but also their behaviours, and the learning context/environment. Subprocesses of each of the ten processes were also identified. This study expanded self-regulated learning theory and L2 writing theory and contributed to a better understanding of how EFL learners learn to write. It is expected to inform L2 writing teaching, and to shed light on future L2 writing research.