The Shanghai native and former world number one finished on 25-under par, roared all the way by her hometown crowd, having begun the day one stroke behind Japan's Mao Saigo.
Saigo's one-under 71 left her sharing second place on 19-under with Kim Sei-young of South Korea, who carded a four-under 68.
"It's amazing to be able to win at home," said Chinese number one Yin following a victory romp over the closing nine holes that thrilled her legion of fans in her home city.
"The crowd is amazing, people shouting my name and rooting for me," added Yin, who said she was looking to see her mother but couldn't manage it among the large galleries.
"This tournament really, really means a lot to me and I'm just so happy I'm able to win," she said.
At just 22, Yin now has four LPGA wins including one major - last year's Women's PGA Championship.
Asked what comes next, she said: "We'll see."
"Let me finish today and just have fun with my mom, and we'll think about it later."
Kim, another former number one, had led for the first two rounds after a dazzling 62 on Thursday.
Fourth was Yealimi Noh of the United States, whose final-round 67 left her seven strokes adrift of Yin.
"My best finish of the year, so it's been really nice," said Noh, describing it as a "solid week."
"I just hit it really well which was really surprising and I was grateful... because I had some back problems coming into the week," she added.
World number four Yin immediately wiped out Saigo's lead at the start of the round, carding a birdie on the first.
She edged in front with another on the fifth before her back-nine birdie barrage.
The Shanghai sensation was met with a champagne shower and a roar from the packed crowds around the 18th as a final birdie sealed the win.
"It gives me goosebumps when I think about it right now," Yin told reporters.
"I mean, all the fans, the energy, it's just phenomenal."