Since i've got asperger's i can't avoid to be anxoius during exams at university and this doesn't allow me to think deeply. how could i suppress it?

Several techniques: Many people get anxious taking tests, whether you have asperger's or not. There are medications used for performance anxiety, like having to get up before people to speak or perform. But I have not heard them used for test anxiety. Mostly, learning relaxation techniques can help in this situation. Making sure you have had plenty of sleep, eating regularly, and not having too much caffeine

How about a book?: Would you consider buying and reading a really good book? It is called: "the relaxation response" and is by herbert benson. The book explains a process you can practice which will teach you how to calm down and relax. The technique only requires 5 or 10 minutes once or twice a day to master. If it helps, you may be able to work to your full potential on exams without medication. Good luck.