It was the 28th red card of Ramos’ career across all competitions, per ESPN Stats & Information.
“I will talk with the players because a lot of games are coming up and we need the maximum number of players,” PSG coach Christophe Galtier said.
“Missing games because of stupid suspensions and stupid bookings, we must fix that.”
Reims are 14th on eight points.
The hosts played boldly but PSG had the best chance through Mbappe, who was denied from close range by Yehvann Diouf in the 33rd minute.
Ramos, however, picked up a yellow card after arguing with referee Pierre Gaillouste, who an instant later went back to the Spaniard and handed him a straight red card.
Earlier, Marseille’s second place was under threat on Saturday as they were outfoxed by promoted Ajaccio.
At the Stade Velodrome, Payet opened the scoring with a spot kick after a Cedric Avinel handball in the 15th minute.
Ten minutes later, however, Moussiti-Oko outpaced the Marseille defence to beat Ruben Blanco with a left-footed effort.
The visitors went ahead two minutes into the second half when Balerdi deflected Youssouf Kone‘s cross into his own net and Marseille’s only clear chance then came in the 55th minute when Oumar Gonzalez almost scored an own goal, too. (Reporting by Julien Pretot; Editing by Christian Radnedge)
Information from the Associated Press was used in this report.