The study time of foreign doctoral students varies with different countries, schools and majors. In the United States, it takes about 4-6 years to complete a doctorate. This time includes the course study, research stage and the process of doctoral thesis writing and defense. In Britain, most schools have 3-4 years of doctoral education. The doctoral system in Australia is usually 3-4 years. It should be noted that these time frames are approximate estimates, and the specific study time will be adjusted according to the individual research progress and the requirements of the school.