Heres what happen I just did the quest where you should save the moth priest and when I walked out from the dungeon he started to attack me but I made so he went down on hes knees and then he was friendy but that was not the end.
When I went back to the dawngaurd he spawned and started to attack me and when hes on hes knees I can interact with him to start the quest and where ever I go he will spawn and start attack me after a loading screen plz someone help

Check the hints and spoilers forum - someone had a very smilar-sounding problem a while back, and the thread there should help you.

use calm mind on him or if he attacks you take out your weapon and sheath it back try it it might work

If not vampire just attack him until he submits. He will eventually stop attacking. You can seduce him as a vampire and then bite him to make him your thane (follower). As for werewolf just do the same as a human attack until he submits. You can not kill him he is an essential NPC.

well thats what I do but he just go down and I can interact with him and if i got to another place he will spawn and attack me again. even if i load another save he will spawn he spawn after every loading and tries to kill me and I can take him down but cant interact with him after

I did that and waited then he rose and finally talked to him. Don't have any problem with him at all. Are you a vampire? Are you with the Dawnguard?

Im with the dawngaurds