Trysil is a municipality in Østerdalen in the Inland with just under 7,000 inhabitants. It borders in the north to Engerdal, in the northwest to Rendalen, in the west to Åmot, and in the southwest to Elverum and Våler. To the south and east, the municipality borders Sweden. Together with Engerdal in the north, the municipality constitutes a "bulge" on the map so that Sweden surrounds the municipality on almost three sides. The municipality has two settlements - Innbygda in the north and Nybergsund further south, both by Trysilelva. The inn has a town hall, culture house, secondary school and upper secondary school.

The municipality is very sparsely populated where agriculture and forestry have traditionally been the most important industries, and the municipality has several wood processing companies. The Trysilelva was one of the last rivers in Norway to have timber floating, this business was closed down in 1991 - decades after most other places in the country. Moelven Trysil (Trysil Skog) is still located with a large sawmill by the river north of the settlement Innbygda, and close by Coop has a building materials market. Trysil is otherwise Norway's largest moose municipality, with 1,050 moose killed in 2004.

Winter tourism is a growth industry in the municipality, and Trysil has Norway's largest ski resort, Trysilfjellet. From the beginning, the facility was a cooperative with affected landowners, and in 2005 was sold to the Swedish company Skistar for NOK 241 million. Skistar owns cabin cabins, lifts and accommodation under Trysilfjellet, and can thus cross-subsidize the services and ensure high occupancy during the tourist seasons in a way that previous owners could not. There are 31 ski lifts at Trysilfjellet (1132 masl), including six children's lifts. The largest cottage hamlets are Håvi and Trysilfjell south of the mountain, and Fageråsen north of Trysilffjellet.

The inland's first development of wind power on a larger scale, the Raskiftet wind power plant, is located on the ridges west of Lake Osensjøen and was taken into use in 2018.

Trysil is known for its authors (Einar Skjæraasen) and skiers (Trysil-Knut). Trysilgutten, founded in 1861, is the world's oldest ski club, and a civilian ski race was arranged as early as 1855, but it was not the world's first. The municipality's motto is "Stave roof in front".

In the city center Innbygda (2,478 inhabitants), is one of the country's oldest rural museums, Trysil bygdetun, founded in 1901. The museum today includes farmhouses, farm buildings and outbuildings - a total of 21 buildings that show how people in Trysil lived in the 1700s and 1800s . The oldest building is from approx. 1650. Bygdetunet is part of Trysil / Engerdal museum. Trysil / Engerdal museum is a foundation, established in 1994 by Trysil municipality, Engerdal municipality, Trysil History and Museum Association, and Engerdal Museum.

Trysil had direct mayoral elections in 1999, 2003 and 2007, in 2003 Ole Martin Norderhaug (Labor Party) received 59.9% of the votes. Norderhaug was re-elected in the 2011 election.

The town of Nybergsund (371 inhabitants) was bombed by German planes during the attack on Norway on April 11, 1940, when King Haakon VII and Crown Prince Olav stayed here.