Between May and June. Defense is an important form of organized, prepared, planned and evaluated papers. The graduation defense time of domestic colleges and universities is May-June, but the specific time depends on the regulations of each school. Defense is an educational term. Generally, teachers of several related majors put forward some questions according to students' design entities and papers, and at the same time listen to students' personal explanations, so as to understand the authenticity and familiarity of students' graduation design, examine students' adaptability and breadth of knowledge, listen to students' understanding of the development prospects of the discipline, overcome their nervousness, anxiety and uneasiness during the defense, and be confident that they can successfully pass the defense.