The joint fund refers to the fund provided by the National Natural Science Foundation of China and its co-sponsors according to the regulations of the National Natural Science Foundation of China and the management characteristics of the joint fund, in order to standardize and strengthen the project management of the joint fund of the National Natural Science Foundation of China and support the agreed basic research in the field of science and technology. The joint fund is an integral part of the funding system of the Science Fund. According to the operating mechanism and relevant management regulations of the Science Fund, excellent projects are selected for funding and management.