Search engine Baidu is one of the most influential marketing platforms in China, commanding 30% of total online ad spending. Look closely at the strategies of top advertisers and you'll likely find the fingerprints of Liu Wei and her team, who are changing the way brands approach search marketing.

"A lot of people think search engines are just for helping our clients realize online sales. Actually, we help a lot of brands communicate and engage their consumers online to improve their brand image," said Ms. Liu, who also goes by Vanessa, and is Baidu's general manager for search engine marketing.

The 38-year-old leads a team of 150 who work with Baidu's 1,900 biggest advertisers. Baidu has about 80% market share in China by search query, but Ms. Liu is passionate about helping marketers see the possibilities of data analytics and understand how they can better target specific consumers.

Procter & Gamble is one of six major marketers working with Baidu under a "Joint Business Plan" of close collaboration. Baidu found that many potential Olay consumers were asking on the search engine, "What age group is Olay designed for?" In response to this finding, Olay developed a new cream with the message "Hold On to Age 25."

"This product was very successful," Ms. Liu said. "So it wasn't us saying, 'We'll run this ad for you.' It was us analyzing their consumers, their brand and their competition to help them create better positioning."

(The other Joint Business Plan marketers are Nestle, Mercedes-Benz, e-commerce site Yihaodian, Ping An insurance and travel site eLong.)

Mia Xu, senior digital manager at Lancome, described a mutually beneficial partnership with Baidu, with Ms. Liu serving a teacherlike role. "They taught us how to use the data and how to use the data to stimulate demand," she said, but added with a laugh, "We also teach them a lot in brand knowledge, you know!"

Ms. Liu's other initiatives include building new commercial products aimed at brands, finding mobile marketing opportunities such as in-app ads, developing real-time ad-buying processes and creating a system for quantifying online marketing results. She is also dean of the Baidu Marketing Institute, which has trained 180,000 people from brands and agencies on search marketing.

When asked what's her biggest challenge, Ms. Liu said it's the same as her clients'. "The media environment is constantly changing. Users have more and more choices," she said. "With the emergence of mobile internet, how do we better communicate and engage with consumers to create effective marketing?"

Next: Esther Yang