Eva Samkova of the Czech Republic won the six-woman Big Final for the gold medal, edging Maltais in second, and Lindsey Jacobellis of the United States, in third. Maltais leads the overall World Cup standings with 3,400 points.
"I'm really happy with second place and I'm happy for Eva too because I think she deserved that win," Maltais said. "She was riding really strong."
Maltais led most of the way until she was passed by the Samkova near the bottom of the course.
''I made a major error,'' said Maltais. ''The course was pretty chewed up after being perfect all weekend and I lost some control. Still you have to give Eva credit. We were side-by-side the whole way and without my error it would be have been very close at the finish.''
It was Maltais's 35th career World Cup medal and her fourth this season. She won Saturday's race, on the same course as Sunday's, and was second at two World Cup stops before Christmas.
Maltais says having to race on back-to-back days takes a toll on her physically.
"It's really hard. I'm not getting younger," the 33-year-old said with a laugh. "I think those young girls, they get an advantage a bit. This morning I was really sore."
But her stragety, Maltais says, is always the same, regardless of how few or how many hours she has between her events.
"I knew I had to race two races in a row so I sat down with my coaches last night and set up a specific goal for today," she said. "It was a pretty big day — we had to qualify in the morning and race in the afternoon — so considering we were already tired, it was a bit like the scenario we're going to have to face in the Olympics.
"I wanted to qualify well and focus on my specific racing goal and race as well as I know I can do."
Olympic champion Maelle Ricker of Squamish, B.C., finished sixth.
The Canadian men had their best day overall this season with Kevin Hill of Vernon, B.C., a bronze medallist at the season opener last month, reaching the Big Final and placing sixth. Christopher Robanske of Calgary won the small final for seventh overall to equal his best result this season while Robert Fagan of Squamish was 12th.
Caroline Calve of Lachine, Que., was the top Canadian at a snowboard parallel slalom at 13th. Marianne Leeson of Burlington, Ont., finished in 16th place.
Patrizia Kummer of Switzerland won the gold.
On the men's side, Matthew Morison of Blackstock, Ont., was 24th. Vic Wild of Russia was the winner.