There are preconditions for answering this question: the doctoral thesis has been completed; Paper materials have been collected. First draft: one and a half months; Tutor first trial: follow the tutor for a week; First modification: 2 days to 15 days depending on the modification scope; Tutor re-examination: follow the tutor for a week; Finalization: 2 days to 15 days, depending on the scope of change. To sum up, ensure the quality of doctoral thesis and leave enough writing time for three months.