My son is in love with a mushrik(polythiest). I want to know some dua or wazifa to break this haraam relationship. My son is not ready to listen anything.

There is no specific dua apart from the general duas which you should always make for your children. One dua you should recite daily is the dua for ones children and this is found in Saheefa Sajjafiya of Imam Sajjad (a.s). Its an excellent dua and inshallah both you and your children can benefit from it.
If your son is simply not ready to listen, then the least you can do is to explain him that in order not to affect his future generation after marrying a Kaafir woman, he should at least make her accept the shia faith. After doing your duty to your best, leave the rest upon Allah and be calm. By nagging and forcing, you can never amend any relationship whatsoever. Let him experience it if he insists and see the outcome himself. You may never know, she might change her faith and become better than expected such that she could help your son in turn. Many Such incidents have been heard to happen also in my knowledge.
InshAllah things will take their own path but try never to disown your son even if you have to appear otherwise for him to realize his mistakes.