The Inter-American Development Bank（IDB）has become a main financial resource to support social development of the Latin American and Caribbean region since its establishment in December 1959. The regional member countries as a whole subscribed more than 50% of the capital of the bank. In recent years，the IDB has guided many private enterprises to invest social development projects，and has transferred more support from consumer fields to product fields via increasing loans to infrastructure. As the newest member，China subscribed the smallest proportion of Ordinary Capital（OC），but has contributed much more to the Fund of Special Operation（FSO）which provides financing for most vulnerable member countries.