Not less than 30 minutes. According to the requirements of inquiring about the defense of graduate thesis of Lanzhou University, it is known that the doctoral group of Lanzhou University will give a report of not less than 30 minutes. Lanzhou University is a national key university directly under the people of China and the Ministry of Education. Directly under the central government, it is established by the State Bureau of Science, Technology and Industry for National Defense and the Ministry of Education. Ranked among "Double First Class", "985 Project" and "2 1 1 Project", and selected for "Everest Plan", "Strong Foundation Plan" and "2066".