1. At that time, Cao Cao was still a junior, and he still wanted to be a competent minister. Moreover, judging from a series of actions in the early stage, he still advocates maintaining orthodoxy, so Dong Zhuo's misconduct is really difficult to calm down.

2. Eliminate Dong Zhuo in order to improve his reputation and gain political capital for the future. Cao Cao is not a standard aristocratic family, not as good as the Yuan family with four generations under one roof. At that time, it was recognized by the gentry, and the biggest advantage was to improve its reputation.

3. At that time, the strength contrast was very different, and Yuan Shao didn't react strongly to it. Cao Cao decided that "the vertical axis is insufficient", so he acted alone. From the effect, although he didn't succeed, his series of actions laid the foundation for his resourcefulness in the future.