Founder Mark Zuckerberg said, when you log in, there will be a prompt at the top of the news feed.
It will have tips on how to spot and flag stories that are hoaxes, or designed to mislead people.
Zuckerberg said stopping the spread of false news is an important part of building an informed community.
On Facebook Zuckerberg wrote, "We know our community wants accurate information. We've got more work to do, but this is another important step."