The 24-year-old dual world champion was adding this to her victory in the slalom at Spindleruv Mlyn in the Czech Republic six days ago.
Pärson, who was leading after the first leg, posted a time of two minutes 9.94 seconds to beat Nicole Hosp, the Austrian who was quickest in the second leg, by 21 hundredths of a second.
Tina Maze of Slovenia came in .40s further back in third.
Pärson’s third win of the season saw her displace Austria’s Michaela Dorfmeister, only 23rd here, as the overall leader in the World Cup standings on 540 points.
Pärson’s arch rival, Janica Kostelic of Croatia, could only manage sixth in Lienz which, after her victory in the giant slalom at Spindleruv Mlyn last week left her in second overall on 532 points.
This was Pärson’s 29th World Cup success and it confirmed the 2002 Olympic giant-slalom silver medallist’s domination of the technical events in the series.
The final instalment of the Pärson v Kostelic rivalry for 2005 takes place Thursday here with the last slalom of the year.
It resumes on January 5 in Kostelic country on the slopes of Zagreb ahead of the showdown in Turin at the 2006 Olympics between February 10-26.