China's biggest lender, Industrial and Commercial Bank of China, aims to raise up to $21bn (£11bn) when it floats on 27 October, Chinese media has said.
ICBC's share listing is likely to attract overseas investment
Such a move would set a global record high for a share flotation.
The report, in the state-run China Business News, came as the bank's executives presented their share sale proposals to investors.
The bank is set to float on both the Shanghai and Hong Kong markets in a dual listing, selling 15% of the firm.
China's surging economy has created huge demand for banking services and forced the sector to modernise.
International share offerings are part of this process - since June 2005 four lenders have raised $25bn by listing.
ICBC was set up by the Chinese government in 1984 and has 21,000 branches, 360,000 staff and 150 million customers.
In a recent statement, it said it expected to earn a net profit of $6bn this year, compared with $4.3bn in 2005.
The current record for the world's largest initial share flotation is $18.4bn, which was raised by Japan's NTT Mobile Communications Network in 1998.