Leading Stacy Lewis by a shot going into the final day, Feng trailed her American rival by the same margin as she teed off on the par-five 18th.
With Lewis having signed for a 68 and an overall 25 under par, she could only watch as Feng eagled the last, almost finishing with an albatross two.
Feng was certainly a popular winner in her home country, with her brilliance bringing her a 10th career success.
It also brought to an end a brilliant tussle between the pair, with Inbee Park their nearest challenger four shots back on 21 under.
Feng was playing catch-up for most of the day, despite having held the overnight lead, after Lewis picked up four birdies over her first six holes to go two clear.
But the 24-year-old Chinese player kept her cool and went on to secure a victory which she claimed was just as satisfying as when she won the Wegmans LPGA Championship last year.
"I would say I'm as happy as when I won the major last year," she said on www.lpga.com.
"This is our first time to have an LPGA event in Beijing, and Reignwood is my new sponsor, so I really wanted to do well to make them look good. And I think I did a great job. I broke my low score for four rounds, and I think I gave all my best."
Feng continued: "She (Lewis) started really great with four birdies in the first six holes, and I went from leading by one to down by two.
"I knew that she's always a great player. I expected her to make a lot of birdies. And I'm always like, a slow, slow player. I usually play better on the back side. So I knew it was an 18-hole challenge, and only the first six wouldn't affect the whole result."