The 10th seeded Hyderabad based shuttler needed just 47 minutes to defeat her fourth-seeded opponent 21-16, 21-19.
Saina thus became the first ever women’s singles player to reach eight consecutive quarter-finals at the Badminton World Championships.
Saina will meet seventh seed Carolina Marin of Spain in the last eight stage. Marin defeated 15th seed Sayaka Sato of Japan 21-7, 21-13 in the third round.
Saina took her time to settle down and Intanon gave her a tough time in the early stages of the opening game. Intanon was leading 8-5 at one point, but Saina took six consecutive points to take the lead.
The Indian continued to dominate after the break to take the first game by a comfortable margin.
The second game was a tighter affair with both players fighting neck and neck till the very end. But with the scores tied at 19-19, Saina took two back to back points to clinch the issue.