Saina, who won the tournament in both 2009 and 2010, earlier had played with Ji Hyun Sung of South Korea to enter its final for the fourth straight year while Xuerui pipped compatriot Wang Yihan in the other semi-final.
On Saturday, the World No 5 established a comfortable lead in the first game before Ji Hyun Sung staged a stunning comeback. The latter restored parity at 17 all and even inched ahead to 20-19 but Saina did not give up and reeled off three points to win the game.
She bettered the feat by winning five points in succession when Sung was leading 16-13 in the second game. That probably demoralised the Korean who could not return Saina's forehand smash on match point.