While it is her first trip to Beijing as Treasury secretary, Ms. Yellen is no stranger to China. In her role as president of the Federal Reserve Bank of San Francisco, she had regular contact with Chinese officials, and as chair of the Federal Reserve from 2014 to 2018 she would meet with officials from China’s central bank at international gatherings. Ms. Yellen’s credentials as an academic economist have made her a welcome emissary in Beijing. “They like her very much because she looks at the world in economic terms, and they’re extremely comfortable with that,” said Craig Allen, the president of the U.S.-China Business Council.