Wales made promising start but Canada secured four-try bonus and led 28-0 at half-time thanks to McKinley Hunt's double and scores by Alysha Corrigan and Asia Hogan-Rochester.
Welsh number eight Georgia Evans yellow-carded for a high tackle in 48th minute, followed by Taylor Perry and Brittany Kassil going over for Canada.
After heavy loss to Scotland in opening match, Wales were nilled and are set for a group-stage exit.
Canada, ranked second in the world, have shown their credentials as challengers for the trophy by cruising past Fiji and Wales.
Canada 42-0 Wales
Image source, Getty ImagesIrish television match official (TMO) Leo Colgan is again keen to be involved and spots a high tackle from replacement Canada prop Olivia DeMerchant who is shown a yellow card.
So Wales and Lleucu George have another chance but while the kick to touch is successful, Wales were held up over the Canada line.
Canada 42-0 Wales
Just when you thought Wales might respond with an attacking platform, fly-half Lleucu George misses her kick to touch.
Canada 42-0 Wales
Siwan Lillicrap
Former Wales captain
We are seeing outstanding brilliance from Canada but Wales have got to dust themselves off and enter this next 20 minutes with everything they've got.
Canada 42-0 Wales
Sioned Harries
Former Wales captain on BBC Radio Cymru
Wales were then walking back to their place for kick-off after the latest Canada try.
Not a single player is showing passion, enthusiasm, no desire to go again.
The attitude and body language from Wales is so negative.
Canada 42-0 Wales
It is a special day for the Metcalfe family as 18-year-old Branwen comes on for her international debut alongside her older sister Nel.
Branwen slots into the back-row while Nel is a full-back.
Canada 42-0 Wales
Caryl James
Former Wales wing on BBC Radio Cymru
Canada are doing just what we expected from them, they're so powerful.
It's a real battle for Wales and they need to keep with it.
Canada 42-0 Wales
Heather Lockhart
Former Scotland prop
Canada have got such a mix of this power play in the lineout, the forwards and the passing.
It's not just the passing in the backs, it's across the backs and forwards and the overall interplay.
Brittany Kassil (Sophie de Goede con)
Canada are showing no mercy here as replacement prop Brittany Kassil dives over from a powerful maul.
The flawless lock Sophie de Goede slots over her sixth conversion.
Canada 35-0 Wales
Siwan Lillicrap
Former Wales captain
It's relentless from Canada, the forwards, the gain line, the work they're doing. There is a reason why they are ranked second in the world.
Taylor Perry (Sophie de Goede con)
Image source, Getty ImagesCanada can not be held back for long as fly-half Taylor Perry crosses for the fifth converted try.
Georgia Evans' yellow card will stay as just that after a bunker review.
Canada 28-0 Wales
Siwan Lillicrap
Former Wales captain
It's the right call by Hollie Davidson, she's an outstanding referee.
That's a huge loss for Wales around the field Georgia [Evans] has had a really good game
The amount of tackles she's made, she's been exceptional.
Canada 28-0 Wales
Nick Webb
BBC Radio Wales commentator
This has been great play from the Canadian forwards.
If they weren't playing Wales, we'd be really enjoying it!
Canada 28-0 Wales
Number eight Gabrielle Senft had appeared to have scored Canada's fifth try but Ireland's television match official Leo Colgan picked up two incidents.
First of all there was a knock-on by Canada in the build-up but then Wales number eight Georgia Evans is shown a yellow card for a high tackle.
Score remains the same but Wales are down to 14 players.
Canada 28-0 Wales
Siwan Lillicrap
Former Wales captain
I think we'll see some changes quite early on in the second half to the Welsh front row.
You've got experience on the bench with Kelsey Jones and Gwenllian Pyrs, so maybe they need some stability now.
Canada 28-0 Wales
Canada have been dominant in the scrum and they force Wales to give away an early second-half penalty, while the Welsh lineout continues to malfunction.
Canada 28-0 Wales
Siwan Lillicrap
Former Wales captain
Wales have shown some promising moments in the first half, the way they played down in Canada's 22 applying pressure.
They weren't able to convert it into points and that's the next step now. Execution when it matters.
Canada 28-0 Wales
Caryl James
Former Wales wing on BBC Radio Cymru
Wales' attitude has been far better today, but Canada's fitness, skill and class is just too much.
Canada 28-0 Wales
We are under way in Salford as Canada look to extend the lead against Wales.
HT: Canada 28-0 Wales
Philippa Tuttiett
Former Wales international
The first 10 minutes of the second half is going to be important for Wales. If Canada come out firing then we could be a big score line.
If Wales come out with that same fight and intent, then maybe we could have a bit of a game on our hands.
HT: Canada 28-0 Wales
Image source, Getty ImagesAfter Canada and Wale finish, Scotland face Fiji as the second part of the Salford double-header (14:45 BST).
Unless there is a massive Welsh upset then the Scots will be looking to seal a quarter-final berth.
There are then a pair of fixtures in Pool A with England expected to breeze past Samoa in Northampton (17:00 BST).
That is followed by the USA versus Australia in York (19:30 BST), which is pretty much a shoot-out.
The Americans were overpowered by the Red Roses on opening night while the Aussies, who thrashed Samoa, finish against the hosts.
