Three goals in the opening 33 minutes left the visitors climbing a mountain they never looked likely to scale.
Dean Cox put Orient on the victory path in the 12th minute with a 25-yard free kick which flashed just inside the post after Scott McGleish was fouled.
Then two goals in as many minutes had the home crowd roaring their approval. Swindon keeper Phil Smith could only push away a McGleish header and Alex Revell followed up to nod in his 14th goal of the campaign.
Skipper Stephen Dawson then beat keeper Smith from 25 yards to further underline Orient's dominance.
The nearest Swindon came to scoring was in the 18th minute when the base of a post kept out a 25-yard effort from Matt Ritchie.
Jamie Jones also did well to hold on to a Paul Caddis drive in the second half, but, generally, it was Orient who looked the more dangerous and just before the end only the woodwork prevented a fourth goal from substitute Jason Crowe.
Orient have now only lost one of their last 18 matches in all competitions.
Leyton Orient 3-0 Swindon: Match Report - view commentary, squad, and statictics of the game as it happened.
Source: DSG
