A second consecutive five-wicket haul from Wanindu Hasaranga skittled Oman for 98 - the second-lowest ODI total in their history - as Sri Lanka cruised to a ten-wicket win.
The result means Sri Lanka have one foot in the Super Sixes with two wins from two.
The win set up by Hasaranga with figures of 5 for 13 was finished off by the Sri Lankan openers, who completed the chase in 15 overs.
Dimuth Karunaratne notched his 10th ODI fifty in the process.
The nature of the win has also given a significant boost to Sri Lanka's net run rate - something which they will be able to carry over to the Super Sixes stage, provided Oman qualify.
As for Oman, they remain in a good position to make the next round despite this defeat, with two wins from their three games.
(ESPN cricinfo)
