One year. The interval between student tickets was changed to one year. Changing the train ticket is the behavior of passengers to modify the travel time, arrival place and other information of the purchased train ticket. Student tickets refer to students and graduate students who study in ordinary colleges, universities, military academies, middle schools, primary schools, secondary specialized schools and technical schools, and whose family residence and school are not in the same city, and are sold at a reduced price with the official seal of the colleges and universities.