Multilateral development banks （MDBs） have made a great contribution to global economic development in past seventy years. At the same time they have accumulated many disadvantages. From the beginning of this century，the rising emerging economies as a whole and their growing demand for the infrastructure construction capital highlight the inadequacy of the infrastructure funding supply in existing MDBs system. In order to solve this issue，the emerging economies endeavor for expansion and modification the existing MDBs，as well as building the new MDBs. Two new MDBs are under construction：the BRICS Development Bank and the Asian Infrastructure Investment Bank，which are both market-operated professional MDBs for infrastructure financing. The former MDB belongs to multi-countries cooperation in the BRICS group，while the latter one is based on the voluntary cooperation among Asia countries. The construction of these two banks reflects the characteristics of specialization，diversification and democratization. Through the innovation cooperation in currency payment，credit ratings，financial audit and many other fields，the new MDBs will benefit for the economic soft power of emerging economies. The buildup of new MDBs will also promote the competition and the development among the MDBs system. The effort of emerging economies would gradually push forward democratization of global financial governance，and create a more suitable and ideal international development finance environment.