The amount of money funnelled into NSW government coffers from fees charged to train passengers passing through station gates at Sydney Airport has surged by 27 per cent over the past year to almost $69 million.

And in further evidence of the staggering growth on the rail line to Australia's busiest airport, the latest accounts for the private operator reveal total patronage across its four stations – including Green Square and Mascot – surged by almost 22 per cent to 18 million people in the year to June.

The growth resulted in Airport Link Company paying the government $68.6 million in a "train service fee" this year, up from $54 million in 2014-15, and $27.2 million in 2013-14.

The increase in travellers using Sydney Airport, combined with road congestion encouraging more people to catch trains, mean the government is set to reap further windfalls in the coming years from the station access fees paid by passengers.