This course tells the basic concepts and principles of Geochemistry, and their applications in different fields of Earth Sciences. Main contents of the course include: (1) to study the chemical compositions, textures and evolution of different rocks, minerals and fluids in lithospheres (mantle and crust) and hydrosphere using modern geochemical principles and analytical methods; (2) to study magma origin and evolution, subduction zone processes, evolution of orogenic belt, ore-forming mechanism, surface processes (e.g., continental weathering, marine sedimentation, and paleo-environmental/climate change) and planetary evolution by application of trace elements and isotopic tracing, and isotopic fractionation principles.