Victory over Hubert Fournier's side takes the capital club 16 points clear of Monaco, who host Nantes on Sunday, though defeat for Claudio Ranieri's side will give PSG the chance to wrap up their second successive title next week at Lyon.
Coach Laurent Blanc was shorn of injured top scorer Zlatan Ibrahimovic, but he will have been buoyed to see Edinson Cavani move to his favoured position down the middle with ease and score the game's opener.
The Uruguayan's replacement on the right wing, Lucas Moura, had a big hand in adding a second just after the break, with Aissa Mandi putting through his own goal.
PSG used the opportunity to rest several key players ahead of Tuesday's UEFA Champions League quarter-final second leg at Chelsea.
Below-par in the week, Cavani was razor-sharp throughout the first half and went close 14 minutes in after racing onto Adrien Rabiot's pass, but Mickael Tacalfred recovered well to deny him.
Reims' attacks were few and far between but Odair Fortes almost caught Salvatore Sirigu out with a long-distance effort.
And PSG's dominance was finally rewarded in the 43rd minute as Cavani slotted home after good work on the right from Gregory van der Wiel.
The first half had seen Blanc's side frustrated, but they were quick to strike again after the break.
PSG's left-back Lucas Digne fashioned an opening down the left before the teenager's cross was headed towards goal by Lucas and deflected in by the hapless Mandi.
Mandi then passed up a chance to redeem his earlier slip, heading Floyd Ayite's free-kick over the crossbar as PSG sat back in hopes of preserving their lead.
