The development of geophysics in the 20th century is reviewed and a perspective look into the 21st century is presented briefly. It is pointed out that the 20th century is an important historical period in the development of geophysics. The fulfillment of a large number and large-scale global research projects conducted in the 20th century has made human being acquiring a deep understanding of the Earth as a whole system. It has provided the information of the Earth’s internal processes and space factors, related to the natural resources, energy resources, natural disasters and environment, and has broadened our field of view to the Earth as a whole system. It has also stimulated the study to the coupling between the space, the Earth, including the continent as well as the ocean, and ecological environment, and has achieved a great success in benefiting the human being. It is also pointed out that the geophysics will continuously play an important role in attacking a series of outstanding problems in the Earth sciences. It will continue making great contribution to the understanding of the Earth as a whole system, and the solar-terrestrial system and the solar-terrestrial interrelation, to the quantifying the coupling between the spheres inside the Earth's interior and the complicate fabric of the state of the Earth’s interior, and to the issues of water, natural resources and environmental, including space environment.