Crop germplasm are basic resources for global food security and sustainable development and material base for original innovation of agricultural science and technology and development of modern seed industry. The science of crop germplasm resources is a scientific discipline devoting to the research on diversity and its use of crops and their wild relatives. The three basic theories of the science include the theory of centers of origin of cultivated plants， the law of homologous series in variation and the synergistic evolution theory of crop germplasm resources and cultural environments and social development. The basic attributes of the science include genetic diversity， genetic specificity， genetic integrity and genetic accumulativeness. The science covers theories， technologies， management and systems involving in survey， conservation， evaluation， research， germplasm enhancement and sharing service of crop germplasm resources. This paper establishes the theoretical framework of the science of crop germplasm resources， defines basic concepts and attributes related， and proposes development strategies of the science， esp. in China.