Can i finish this quest???
coz ive found a lot of books for the orc
and it seems that he will not give me another request again....

Is that the "Souls: Black and White" book quest? If so, it's bugged. If you picked up the book before getting the quest, it won't let you complete it and you'll be stuck with a book in your inventory that's listed as a quest item. However, if you're on PC, you can fix it with a console command. Check out the following:

http://www.uesp.net/wiki/Skyrim:Find_the_copy_of_Souls,_Black_and_White

Edit: Apparently it's not just the "Souls" book that's bugged. That just happens to be the one I always pick up first by accident....