According to the bank, previous calculations have overestimated the size of China's economy by about 40%.
The revelation came after the bank updated the way it calculated the country's gross domestic product (GDP).
The bank said the findings meant China would not become the world's biggest economy in 2012 as forecast. It also meant China was poorer than estimated.
This in turn would influence future aid and investment plans, the World Bank said.
China gains extra aid from international institutions and has asked for help in climate change talks because of its status as a developing country.
Read more...http://news.bbc.co.uk/2/hi/business/7148695.stm
