Maud Coutereels gave Belgium a first-half lead with a header from a corner at the Stadion Den Dreef, Leuven.
And it was 2-0 when Scotland lost possession in their own half and Lien Mermans punished them.
Tessa Wullaert made it three with a left-foot shot into the top corner, and Jassina Blom scored twice late on to complete Scotland’s misery.
With nine players unable to make the trip through injury, and Chelsea teenager Erin Cuthbert released to captain the Under-19s, who qualified for their own Euros last week, there were plenty of opportunities for fringe players.
The only new cap in the starting XI was 29-year-old English-born central defender Vaila Barsley – who had never been in a Scotland squad before this game, having previously played for England Under-17s.
On a bad night for her side, she was to prove Scotland’s best player until she was substituted on the hour.
The six-foot defender partnered captain for the night Ifeoma Dieke, with Shannon Lynn again preferred in goal to Gemma Fay, who has yet to play 90 minutes this year.
The first 15 minutes were as good as it got for the Scots. They even created the first chance in the opening 60 seconds when Lisa Evans cut in from the right and tested Nicky Evrard with a 20-yard shot.
Once Belgium settled into their stride it was only a matter of when they would score as the Scots were giving the ball away cheaply when in possession.
Glasgow City midfielder Leanne Ross did so just inside her own half – and although Janice Caymen hit the bar with her ambitious 35-yard lob over Lynn, the goalkeeper could only scramble the rebound from a corner.
From that Coutereels put Belgium into the lead. The goal, just after the half-hour, was all that separated the sides – but the goals the home side deserved came in the second period.
Lynn made a string of good saves but was finally beaten by Lien Mermens after Dieke was dispossessed 20 yards out.
One of Belgian’s star players, Wulleart, then scored the best goal of the game just before the hour, lashing the ball home from the edge of the box.
The pace went out of the game but substitute Jassina Blom scored twice late on to put the seal on her side’s dominant performance.
Barsley’s replacement was another central defender who had never been in a Scotland squad before. Sophie Howard was born in Germany to British parents and plays for Hoffenheim, but by the time she came on for her fellow debutant Scotland were already a lost cause.
Scotland head coach Anna Signeul: “It’s really tough to take any positives – I feel sad for the players who haven’t been in the squad before that this was their first experience of playing for Scotland.
“Even players that have many caps couldn’t live up to their normal capacity. It’s disappointing.
“Shannon had some great saves also – it could have been even more.
“It wasn’t a good start to the second half. I feel sorry for Iffy (Dieke). She did some really good things in the first half.
“One thing I will say about the players is that they worked all game. They didn’t give up.”