863211 is correct about staying for a longer period in China before you come to the United States again.
However you don’t have to wait for such a long time if you have legitimate reasons. Before you come again, you need to be prepared to explain why your last stay was so long and you also need to show the evidence of your intended visit. All you need to do is to convince the immigration officer at the border that you are visiting the country in line with the visa you are issued to.
