Background: Critical thinking (CT) is the logical beginning of innovative thinking. Especially for medical doctoral students, critical thinking enables them to apply flexibly existing experience and knowledge to make reasonable judgments and optimal decision through analysis and reasoning on the basis of reflection in the complex clinical situations. The present study aimed to investigate the current situation of critical thinking of medical doctoral students, and was performed to attribute the factors of critical thinking and optimize the relationship between educational goals and higher-level talents, to formulate a CT training strategy for medical doctoral students based on constructivism learning theory. Methods: A cross-sectional survey of critical thinking was conducted among 343 medical doctoral students from 8 universities by using the Chinese version of the Critical Thinking Ability Scale. SPSS 22.0 statistical software was used to establish database and analyze data. Results: The average score of critical thinking ability of 343 medical doctoral students was 292.43, and the score of truth-seeking in seven traits was lower than the minimum recognition score of 40. Extroverted medical doctoral students scored higher than those introverted in the traits of critical thinking, systematicity, self-confidence and inquisitiveness (P < 0.05). Medical doctoral students with reading habits scored higher than those without reading habit in the traits of total score of critical thinking, open-thinking, analyticity, systematicity, self-confidence, inquisitiveness and maturity (P < 0.05). There were statistically significant differences in the total score of critical thinking, open-thinking, analyticity, systematicity, self-confidence, inquisitiveness and maturity in medical doctoral students with different interpersonal relations (P<0.05). Linear regression analysis found that the personality, reading habits, parental education and critical thinking of medical doctoral students were significantly correlated (P<0.05).Conclusions: 343 medical doctoral students generally have positive critical thinking personality, but the honesty and objectivity of seeking truth are not enough. It is necessary to actively guide students to participate in extracurricular practice and improve their ability of maintaining interpersonal relationships, cultivate students' active reading habits and pay attention to the cooperative education mechanism of tutors, counselors and ideological and political teachers in the process of education, so as to promote students' critical thinking and all-round development.