
Firefighters tackled flames covering 25,000 sq m on Ilkley Moor on Saturday, with helicopters making water drops.
West Yorkshire Police said the men, aged 19, 23 and 24, remain in custody for questioning while inquiries continue.
Bradford Council reiterated a warning for walkers to stay off the moors as crews were damping down.
A police spokesperson said a smaller fire took hold on a different section of the moor on Saturday, with investigations under way to see if it is connected to the larger blaze.

Water jets, beaters and specialist wildfire units are being used in the aftermath, with police describing the blaze as "under control".
Martin Langan, WYFRS incident commander, said: "We've managed to die the flames down but there's a significant amount of smoke blowing into Ilkley."
Image copyright PA Image caption Mark Hunnebell said he had seen "countless" water drops from helicopters on Sunday morning

Mark Hunnebell, who has run White Wells Spa Cafe for two decades, said his business was evacuated when the "fire started to spread towards us" at 19:00 BST on Saturday.
He said: "We've seen some fires here in the past, but I've never seen anything like the scale of this one.
"The helicopters have made countless water drops for most of the morning, they've been backwards and forwards constantly."
Christina Cheney, whose house backs onto the moor near an area known as The Tarn, praised the fire service for keeping residents safe.
"A large swathe of the moor looks quite devastated this morning, we're lucky our homes were all safe in the end," she said. "The same can't be said for so much wildlife."
The Met Office confirmed that Saturday was the hottest day of the year so far, with 25.5C recorded in Gosport, Hampshire.
Forecasters have said the UK is set for record-breaking temperatures over the rest of the Easter bank holiday.





Comment: While irresponsible people (or arsonists) may be to blame for causing this fire, the unseasonably dry and warm conditions that enabled it to happen are quite unusual, and this is the case throughout particular parts of the world and which also seem to be a continuation from last year. Meanwhile in other parts of Europe are seeing much lower temperatures bringing snow, hail and flooding:
- Hundreds lose homes as huge wildfires ravage Russia's Trans-Baikal (20th April 2019)
- National disaster declared as thousands flee South Korean wildfires (5th April 2019)
- Europe's record breaking warm winter leads to unprecedented wildfires (1st March 2019)
- 2nd wildfire in 24 hours hits UK: Arthur's seat in Edinburgh ablaze (27th February 2019)
- Major moorland fire in Yorkshire, UK - In February? (26th February 2019)
And from last year:- Wildfire the size of 50 football pitches breaks out in "tinder dry" New Forest, UK (27th July 2019)
- 'Biggest fire in living memory': Moorland blaze reignites and rages for days in Saddleworth, UK (27th June 2019)
- Firefighters battle for second day three large wildfires which broke out in different areas of Scotland's west coast (29th May 2018)
Also check out SOTT radio's: NewsReal: California Wildfires, Climate Change, And The Impossible Brexit