This is Syrstad's second straight victory in Ski Classics.
Second place went to fellow countryman and Team Engcon teammate Ole Jørgen Bruvoll, nearly 56 seconds behind.
Max Novak, Sweden, finished third - two seconds ahead of Alvar Myhlback, who was 58.4 seconds behind Syrstad.
Like in the race, Olympic skier Myhlback is fourth in the overall Ski Classics standings.
On the women's side, Norwegian Anikken Gjerde Alnæs won, 1.5 seconds ahead of Swedish Hanna Lodin, both competing for Team Engcon. Louise Lindström of Sweden came in third, four-tenths of a second behind Lodin.
Stina Nilsson finished twelfth, just over nine minutes behind the winner.
Gjerde Alnæs leads the overall standings, with one long-distance race weekend remaining.
Due to mild weather in Bodø, the five-mile race was held this year in Sulitelma, Norway.
