Reequilibration is common in fluid inclusions, and it is a key point how to identify the reequilibration and to explain the geological factors which lead to reequilibration. This paper summarizes the mechanism of fluid inclusion reequilibration and the affecting factors of reequilibration, and introduces how to identify the reequilibration in terms of petrography and homogenization temperature characteristics. We conclude that different P—T evolution history can affect fluid inclusions reequilibration. Specifically, when there is a low deformation degree, plastic deformation can be dominant, while deformation degree is high, fluid inclusion may leak and burst, and irreversible deformation can be dominant. A fluid inclusion in brittle mineral with cleavages, suffering intense geologic process and quickly changeable geological background, is more likely to be reequilibrated. What's more, bigger and irregular (especially elongated shape) inclusions are easy to reequilibration. Specifically, reequilibrated inclusions always show needleshape pattern or decrepitation pattern (such as decrepitation haloes), and inclusions of a FIA have different ratio of gas to liquid or phases, with abnormal homogenization temperature. Quantitative simulation and reference standard of fluid inclusion reequilibration need to be established, which is an important research direction of the future study of fluid inclusions.