Facebook's Friend Finder accesses the email account associated with a user's Facebook account and matches the email addresses from his email contact list to other Facebook users, using this information to suggest new friends to add. This can sometimes result in an influx of friend requests from people you may not know closely. You can prevent your profile from appearing in Friend Finder results by adjusting your Facebook privacy settings, allowing only people who you are already friends with to look you up using your email.
Log in to your Facebook account. Click on the Settings (with a down arrow) menu and select “Privacy Settings.”
Locate the “How You Connect” section on the “Privacy Settings” page. Click on the “Edit Settings” link corresponding to that section.
Navigate to the section called “Who can look you up using the email address or phone number you provided?” within the “How You Connect” dialog box. Select “Friends” from the drop-down menu.
Click “Done” to save the changes to your privacy settings.