I have Syrian passport with USA visa. I will travel from USA to Lebanon but I have one stop in Frankfurt. I want to ask if I need visa to stay in the airport in Frankfurt until I have my next flight.
You do not require a transit visa. Reviewing Germany's visa information shows Syria as a nationality that requires possession of an airport transit visa when passing through the international transit area of airports in Germany, but also that since you hold a valid visa for the United States you are exempt from that requirement (item 1 in the exceptions).