Does it cost money to reply to Android SMS quickly?

Mainly depends on each other. If the other party is a mobile Fetion user and has opened Fetion, what you send through the Fetion quick reply box after networking is Fetion, which requires traffic and is free of SMS charges; If the other party is Unicom or Telecom or Mobile without Fetion, or you are not connected to the Internet, you can only send text messages.