I hope I can show 3 items in a page of viewpager, but now I only could set viewpager's padding value and margin value, so it only show one item in a page of viewpager. How can I set the item width? I think if I can set more little width of item, the viewpager will show more items in a page.
Have you tried setting the page margins to a negative value, see setPageMargin(int)? If I remember correctly, I read someone realizing something similar to what you're describing that way.
Alternatively, you could have a look at using a Gallery in stead, although I have to admit I'm not a big fan of them as they seem to be less flexible and more buggy.