Set a target of 351 for victory Bangladesh resuming at their overnight total of 75-1 were dismissed in their second innings for 276 with spinners Rohan Sanjaya and Sandun Mendis doing the damage with eight wickets between them.
Left-arm spinner Sanjaya followed his five wickets for 17 runs in the first innings with figures of 5 for 96 in the second to end with a match bag of ten wickets for 113.
Off-spinner Mendis finished with 3 wickets for 45 after Bangladesh staged a late recovery 174-7 to score 276.
MD Akbar Ali staged a lone fight back with a determined knock of 90 off 113 balls (11 fours, 3 sixes) before being bowled by Sanjaya.
Bangladesh won the first under 19 test played at the NCC grounds by 13 runs.
Scores: Sri Lanka (U19) 226 and 233-9 decl.
Bangladesh (U19) 109 and 75-1 contd 276 in 83.1 overs (Sajid Hasan 36, MD Akbar Ali 90, M Chowdhury 23, M Hasan Joy 26, Rohan Sanjaya 5/96, Sandun Mendis 3/45)
