1. High academic requirements: Wuhan University, as a well-known institution of higher learning in China, has relatively high requirements for the defense of doctoral thesis. The judges' in-depth understanding and strict evaluation of the research content and methods make the defense more difficult.

2. High level of defense judges: As a top university, Wuhan University has a group of experts and scholars with high academic level as defense judges, with extensive and in-depth professional knowledge, which has stricter requirements and evaluation criteria for graduate students' scientific research work and papers, which increases the difficulty of defense.