Busch’s average lap speed of 171.261 mph, set at the end of the 55-minute session at Darlington (S.C.) Raceway, topped William Byron (170.703 mph) and Aric Almirola (170.065 mph).
Busch, who drives the No. 1 Chevrolet for Chip Ganassi Racing, has made 22 career starts at Darlington without a victory. His best finish is a pair of thirds (2017 and 2010).
Alex Bowman ended up fourth and Jimmie Johnson rounded out the top-five.
Completing the top-10 were Kyle Larson, Clint Bowyer, Ryan Blaney, Paul Menard and Martin Truex Jr.
Brad Keselowski, who won this race a year ago, ended up 19th-fastest.