Abstract: Knowledge of element partitioning in the Earth's interior is of great importance, as it can contribute to interpret fundamental geological problems, such as element cycling, ore formation, and the property of supercritical fluid. The concentration and partition coefficients of elements under high temperature and high pressure could be in situ extracted by Diamond Anvil Cell (DAC) combined with Synchrotron Radiation Micro X-ray Fluorescence Spectrometry (SR-μXRF) with high accuracy and high resolution. The element's speciation in various phases could be simulated theoretically, based on geochemical thermodynamics, which helps to reveal the mechanism of element partitioning. The in situ detecting methods of element partitioning under high temperature and high pressure by DAC combined with SR-μXRF and geochemical thermodynamics simulation, and their applications on migration of elements in the Earth's interior, ore formation, the early development of Earth's formation and so on, are summarized in this paper. Studying element partitioning behavior under high temperature and high pressure using the proposed method will become more complex, which needs higher requirements for the temperature and pressure conditions. From this paper, the aim is to update and enrich the element partition data under high temperature and high pressure, which will enhance the understanding of material cycling in the Earth's interior.