Four years. According to the Notice of Southwest University on Adjusting the Basic Academic System for Full-time Doctoral Students issued by official website of Southwest University, the basic academic system for full-time doctoral students has been adjusted to four years since the grade of 2020, and the basic academic system for excellent undergraduate graduates to directly study for doctoral students (direct doctoral students) is five years, and the doctoral students in psychology of Southwest University need to study for four years. Southwest University is a key comprehensive university directly under the Ministry of Education jointly established by the Ministry of Education, the Ministry of Agriculture and Rural Affairs and Chongqing Municipality. It is the first batch of "double first-class" universities in China, with "2 1 1 Project" and "985 Engineering Advantage Discipline Innovation Platform".