Police say the man is a registered sex offender who asks people for money, supposedly for a Vince Young foundation.
Young came to the Eagles this season to back up Michael Vick, but has been nursing an injury.
He has been working with police in Washington.
Young tweeted this information about his alleged imposter.
"Please be aware that there is a man in the dc area that has been impersonating me. He is a career criminal. He is dangerous."
Young also thanked NFL security and Prince George's county police for their help.