The top-seeded An, the reigning Olympic and world champion from South Korea, beat Japan's Tomoka Miyazaki 21-17, 21-6 in the women's singles final.
The South Korean superstar has now won 49 of her 50 matches this season. Her only defeat came against China's Wang Zhiyi in the All England final in March.
By winning the match, An became the first player to win the China Masters three consecutive times.
While it was hardly a surprise that An Se-young claimed the women's singles title, Hong Kong's Jason Gunawan was the big surprise of the tournament by claiming the men's singles crown in his first appearance at a BWF World Tour Super 750 event.
Gunawan, who is merely ranked 32nd in the world, beat fellow Hong Kong, China player Lee Cheuk Yiu 21-9, 21-16 in the men's singles final.
Gunawan became the first Hong Kong, China player to win a BWF World Tour Super 750 or higher-level singles title. It was also the first time Hong Kong, China players had occupied both places in a China Masters men's singles final.