The opening game in a triangular series also involving Australia [ Images ] always smacked of mismatch but Trescothick, who ended 100 not out for his ninth one-day ton, and Andrew Strauss [ Images ] turned it into a nonsense as the home team won with 25.1 overs to spare.
Trescothick hit 16 fours as England won a one-dayer by 10 wickets for only the second time.
Strauss, promoted up the order after England decided to discontinue their experiment of using wicketkeeper Geraint Jones as a pinch-hitter, ended 82 not out.
England were set to chase 191 to win after Steve Harmison [ Images ] took four for 39 and Jon Lewis three for 32.
Australia, the third side in the tournament, take on Bangladesh in Cardiff on Saturday before facing the hosts 24 hours later.
England launched their run-chase at a healthy rate before left-hander Trescothick upped the tempo when Khaled Mahmud came on as first change in the 12th over. His appearance marked the end of the game as a contest to be taken seriously.
Mahmud, a medium-pacer who races in and then appears to bowl slower than he runs, saw his first six balls to Trescothick disappear for four fours and 21 runs.
Surprisingly, Mahmud was reintroduced to the attack later. His three overs cost 39.
England's bowlers enjoyed themselves as much as their batsmen after Bangladesh were put in on a murky day.
The opening innings lasted 45.2 overs and could have ended earlier still but for Aftab Ahmed, who made a half-century and put on 76 for the seventh wicket with tailender Mohammad Rafique (30).
Lewis, on his debut and England's matchwinner in the Twenty20 [ Images ] game with Australia on Monday, caused the early damage with a 17-ball burst which gave him three wickets for nine runs.
The score became 39 for three when Nafees Iqbal opened the face as if to guide the ball to third man, with three slips in place, and nicked it behind.
Harmison then outdid Lewis for his second four-wicket haul in one-dayers.
Ahmed faced 56 balls and hit four fours and two sixes for his third one-day half-century.
Tushar Imran played a Harmison lifter down into the base of his off stump, Habibul Bashar top-edged a flat-bat drive which keeper Jones did well to clasp high above his head and Khaled Mashud gloved behind to make it 76 for six.
Harmison also got rid of Mahmud, who spooned a simple catch to Kevin Pietersen [ Images ] close in on the leg side.
Javed Omar lbw Lewis 13
Nafees Iqbal c Jones b Lewis 19
Mohammad Ashraful c Flintoff b Lewis 0
Tushar Imran b Harmison 10
Habibul Bashar c Jones b Harmison 19
Aftab Ahmed run out 51
Khaled Mashud c Jones b Harmison 1
Mohammad Rafique c Harmison b Gough 30
Mashrafe Mortaza [ Images ] not out 29
Khaled Mahmud c Pietersen b Harmison 0
Nazmul Hossain c & b Gough 6
Extras: (lb-4, w-4, nb-4) 12
Total: (all out, 45.2 overs) 190
Fall of wickets: 1-19, 2-19, 3-39, 4-57, 5-72, 6-76, 7-152, 8-159, 9-159
Bowling: Gough 8.2-0-33-2 (3nb), Lewis 10-0-32-3 (1-w), Harmison 10-0-39-4 (1-nb, 2-w), Collingwood 8-0-36-0, Flintoff 9-2-46-0 (1-w).
M.Trescothick not out 100
A.Strauss not out 82.
Extras: (lb-5, w-1, nb-4) 10
Total: (for no loss, 24.5 overs) 192
Did not bat: M.Vaughan, P.Collingwood, A.Flintoff, K.Pietersen, G.Jones, V.Solanki, J.Lewis, D.Gough, S.Harmison.
Bowling: Mashrafe Mortaza 6-1-33-0, Nazmul Hossain 7-0-61-0 (1-nb, 1-w), Khaled Mahmud 3-0-39-0 (3-nb), Mohammad Rafique 6-0-40-0, Aftab Ahmed 2.5-0-14-0.
Result: England won by 10 wickets.