The long development course of traditional geography before 20th century is summarized, and geographical connotation and field-related characteristics are also discussed. Since middle 20th century, geography has not only broadened its field-related of research, paralleling progress in the fields of society, economy, science and technology, but has achieved unprecedented theoretical, methodological and technological progress. The current frontier of geography is a unified disciplinary system with multiple branches, and this tendency of disciplinary synthesis and differentiation corresponds with trends in the development of modern sciences. The introduction of new theories, new methods and new technologies has greatly promoted systematic analysis and synthesis within geography, and thus elevated both the theoretical level and practical usefulness of geography as a scientific system. Looking through into 21st century, there is little doubt that the development of geography would take new opportunities and that sustainable development of geographic environment would become the core of geographic researches. Under the impact of the tide of the 3rd great scientific integration, it is necessary to reform the traditional geography by reconstruction of new systems and methodologies, to examine closely the scientific value and function of geography, and to make further explorations and advances in theoretical and practical fields uninterruptedly, so that the potential energy of science of geography can be released out.