Leading 37-27 at the break, North Dakota State (4-2) broke away midway through the second half with a 14-0 run bookended by Carlin Dupree buckets to make it 72-46 with 4:25 to play and protected the lead down the stretch.
A.J. Jacobson contributed 15 points, Chris Kading added 13, Kory Brown had 11 and Dupree finished with 10 plus seven rebounds for the Bison, who shot 50 percent from the floor and hit 11 of 23 from 3-point range.
Montana State (1-5) kept the score close through most of the first half, closing to 29-26 on an Eric Norman layup with 3:43 to go before intermission, but couldn't capture the lead.
Michael Dison led the Bobcats with 17 points.