I have pasport algerien i want visa transit...

If you want a transit visa through Shanghai, you need a category C visa. The application process is done at the Chinese embassy,  attache to the application: A passport valid for at least six months and contains blank pages to place the visa on and bring a copy of the passport information page and the page that contains the photo separate from the information page, in addition to an airline tickets (or train or ship ones) with the date of confirmation and the seat number to the country or region of destination.