Geochronology provides temporal coordinates for Earth and planetary sciences, enabling the quantitative analysis of the sequence and timescales of geological processes. After over a century of development, dating techniques have greatly improved in terms of research targets,analytical efficiency, spatial and temporal resolution. Geochronology research has transitioned from merely providing chronological constraints to emphasizing the timescales and rhythms of geological processes, thereby constraining the driving mechanisms of, and feedbacks/interplay between geological events. However, absolute dating techniques based on the decay of radioactive isotopes have a physical limitation to their precision and cannot be infinitely improved. Additionally, their temporal resolution generally deteriorates with increasing age, making it difficult to meet the high temporal resolution requirements of deep time research. Developing relative dating techniques whose temporal resolutions are not constrained by absolute age is an important direction for the development of geochronology. This paper focuses on diffusion chronology, a relative dating technique with significant potential which remains to be fully explored. Building upon a systematic review of its theoretical foundations and analytical techniques, the paper discusses key issues that limit the accuracy and precision of diffusion chronology, such as the uncertainty of diffusion coefficients, assumptions about initial boundary conditions, and the quality of measuring concentration profiles. The paper also reviews some recent important advances in diffusion chronology in areas such as magma storage and migration, timescales and rhythms of oreforming, and metamorphic processes. Accurate diffusion coefficients are essential for conducting diffusion chronology research. For example, the differences in diffusion coefficients of Ti in quartz obtained from three experiments can exceed three orders of magnitude. Consequently, the calculated storage time of felsic magma above the solidus can vary from decades to millions of years, significantly affecting our understanding of magma storage conditions. Highquality measurements of elemental concentration profiles are critical for diffusion chronology. Due to the challenges in accurate measurement of titanium content in quartz with high spatial resolution, CL grayscale is often used as a proxy for titanium content. However, this requires consideration of the effects of elements such as aluminum on CL grayscale, and a rigorous evaluation is warranted for the impact of spatial mismatch between titanium content calibration curves (measured by EPMA or LAICPMS) and diffusion profiles (derived from CL grayscale). UPb dating of hightemperature metamorphic processes typically yields relatively dispersed apparent ages, which are interpreted as a long duration of metamorphic processes. This can be partly explained by the open isotopic system behaviour due to diffusion at high temperatures. Looking into the future, to meet the high demand of high temporal chronological data in deep time research, further advancing diffusion chronology in hightemperature systems, and expanding its application under medium to lowtemperature conditions, and integrating it with absolute dating are important avenues.