First of all, you should select the most important part of your topic and make a PPT with data that can speak for about 50 minutes. Since I don't know your major, I'll give you a general description of my major first. I study chemistry.

The PPT of defense is divided into three parts, which are interrelated and extend from one level to another. At first, it's the title, then the second chapter is the subtitle and outline, and then about 3-7 films are used to tell why you study this, the so-called introduction. Then talk about three parts step by step, and make a summary of each part to prove that you want to summarize the upper part and open the next part. Finally, it is a summary, summarizing three parts, which is simple and focused.

Followed by the papers published during the doctoral period, the awards won, the meetings attended, and then thanks, thanks to teachers, classmates, parents, lovers, collaborators and so on.