China is poised to surpass the United States to become the world's largest e-commerce market this year, according to consultancy Bain & Co.

With forecast 32 percent average annual growth, online shopping expenditures in China are set to reach 3.3 trillion yuan ($539 billion) by 2015, the consultancy said in a report.

The study was based on a survey of more than 1,300 shoppers in China across a range of cities, ages, educational backgrounds and income levels.