England won the toss and invited Sri Lanka to bat first and Sri Lanka scored 241 at the end of the 50 overs, losing nine wickets.
Dananjaya de Silva obtained 91 while Dasun Shanaka got 47.
England chased Sri Lanka's score very easily, having scored the winning run in 43 overs, only giving two wickets.
England skipper Eoin Morgan scored an unbeaten 75 runs while Joe Root got 68.
The series has three one day matches and England has already won two.