There were two changes in the Swansea line-up. Mark Gower and Dorus de Vries coming in for Joe Allen and Dimi Konstantopoulos.
The Swans took two minutes to open the scoring when Jason Scotland pushed his way into the danger area.
He robbed Sean St Ledger and, when the ball ran loose, Jordi Gomez raced in to slot past Andy Lonergan into the visitors net.
Darren Pratley left the field holding his shoulder in the tenth minute and was replaced by Guillem Bauza.
The Swans doubled their lead in the 29th minute with Scotland's 14th goal of the season.
The move started with a throw from de Vries to Gower down the left and he made progress before releasing to Scotland, who lashed his shot into the corner of the net.
One minute before the interval a Richard Chaplow shot flew just wide, but it showed Swansea's superiority as that was the visitors' first goal attempt in the opening period.
The second half opened with the Swans pressing the visitors' defence.
Nathan Dyer was seeing plenty of ball and making good use of it with his pace down the right flank.
It was Dyer who almost made a third goal for the Swans on the hour when he slipped a pass inside to Bauza but Lonergan came out of goal quickly to block.
Not to be outdone, another run by Dyer in the 69th minute brought the Swans a third goal when this time Bouza made no mistake from close range.
An injury to Ross Wallace meant that a poor Preston side were forced to play out the final six minutes with only ten men after using all their substitutes.
They were unable to keep Swansea at bay and, two minutes from time, Alan Tate curled a 30-yarder into the net to complete the rout.
There was just time for a Preston consolation when Jon Parkin worked the ball to Chris Brown, who netted from close range.