Long Beach State (5-4) shot 14 for 25 from 3-point range (56 percent).
The 49ers led 30-26 at halftime and started the second half outscoring New Mexico State 18-11 to build a double-digit lead that was never seriously threatened.
Pascal Siakam led New Mexico State (5-3) with 14 points and 11 rebounds. Ian Baker added 10 points and Tanveer Bhullar had eight rebounds. The Aggies shot just 33.3 percent from the field going 18 for 54.
The game was the 40th meeting between the two teams in a series that started in 1981 and was last played in 2008. They met annually as members of the Big West Conference from 1984 to 2000. The Aggies lead the series 21-19.