Brian McDermott's men overcame Championship opponents thanks to goals from Pavel Pogrebnyak and Adam LeFondre.
The Premier League newboys were always in control and took the lead early on as Pogrebnyak smashed home after good work down the right from Garath MCleary.
The Royals extended their lead in the second half, Pogrebnyak again influential, releasing Hal Robson-Kanu down the left, the Welsh winger cut back into the area and LeFondre was on hand to tuck home.
Jay Tabb wasted a good opportunity to score another for the home side and Jermaine Easter missed an open goal in stoppage time for the Eagles to seal victory for the men from Berkshire.
Michael Laudrup rounded off his side's pre-season preparations with an enthralling draw against Bundesliga side Stuttgart at the Liberty Stadium.
Swansea went behind early on when Arthur Boka's free-kick was not cleared and Christian Gentner popped up to score before Vedad Ibisevic weaved his way through the defence before finishing with a low left-footed shot.
The Swans got themselves back into the game after half-time, first Danny Graham slotted home after Michu had played him though.
Graham then scored again from the penalty spot after Nathan Dyer had been shoved in the area. Dyer then gave his side the lead soon after with a deflected effort.
The home side failed to hold on to their lead, however, Raphael Holzhauser finishing calmly after receiving Kevin Stoger's through-ball.
Martin Jol's side were left disappointed after letting a first-half lead slip against Championship new boys Charlton Athletic.
The Cottagers got off to the perfect start in front of their own fans, Alexander Kacaniklic worked well down the left-hand side before cutting to Damien Duff, the Irishman slotting home his first-time effort.
Despite going in at the break behind, Chris Powell's men rallied and pulled back through Johnnie Jackson's finish inside the area.
Moments later they were ahead as Yann Kermogant popped up to hit a surprise effort from 25 yards that flew into the net.