Arsonists torched a building at the derelict RAF Upwood site on Saturday.
Fire crews from Chatteris and Huntingdon were called shortly before 8.30pm to the site and arrived to find a two-storey building ablaze.
The crews extinguished the fire and returned to their stations by about 10pm.
An investigation determined the cause of the fire to be deliberate.
The latest attack follows a similar incident at the site which took place on March 23.
Firefighters from Huntingdon and Ramsey were called at about 5.30pm to tackle a blaze in another of the buildings on the site, which has been vacant for more than 10 years.
Anyone with information about either of the incidents should contact police by visiting www.cambs.police.uk to submit an online report or call Crimestoppers, anonymously, on 0800 555111.
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