Doctoral degree is the highest. Graduate students are the general name of graduate students and doctoral students. China's higher education is divided into three levels: junior college, undergraduate and postgraduate, among which postgraduate is the highest. But graduate students can be divided into master students and doctoral students according to their degrees. Therefore, doctoral students are the highest educational level in higher education. Postdoctoral (postdoctoral) refers to staying in a school or scientific research unit to do research after finishing postdoctoral studies. Postdoctoral students refer to those who engage in academic research in institutions of higher learning or research institutions and serve as researchers in postdoctoral mobile stations or postdoctoral research centers after obtaining doctoral degrees. Postdoctoral research is only two years of research work in scientific research institutions after doctoral graduation, which is equivalent to two years of research and training after doctoral graduation, and has nothing to do with academic qualifications.