Standard Chartered Bank will invest $500m (£332m) in Agricultural Bank of China's floatation in Hong Kong, as it tries to strengthen its position in Asia.
AgBank's initial public offering is aiming to raising $23.2bn
Standard Chartered chief executive Peter Sands said: "This investment is a natural next step in our long-standing relationship and it underpins our recent agreement to develop business together. China is a key market for us and our partnership is a strong symbol of our commitment there."
The two banks are planning to work closely together in the future.