The generation of characteristic fault gases typically accompanies partial discharge and high-temperature decomposition phenomena in oil-paper insulation systems. A deep understanding of the generation mechanisms and diffusion patterns of these fault gases is crucial for the early warning and diagnosis of failures in such systems. Therefore

we first introduce the transport mechanisms of gas in oil-paper insulation. The gas generation mechanisms under electrical and thermal faults

the gas dissolution mechanism based on gas-liquid interphase mass transfer

and the gas diffusion mechanisms from various perspectives are explained separately. Then

starting from microscopic and macroscopic viewpoints

we review numerical calculation and simulation methods for gases in oil-paper insulation

including molecular simulation techniques

multi-physical field coupling

and computational fluid dynamics (CFD) numerical simulation models. Finally

we summarize research findings on gas transport experiments in oil-paper insulation systems from following three aspects: the discharge characteristics and gas generation process

the gas dissolution process

and the diffusion process. Additionally

we analyze the application of gas concentration prediction models in oil. Currently

research on gas transport mechanisms in oil-paper insulation still faces multiple challenges

such as how to improve the gas transport theory

enhance the reliability of experiments

increase the accuracy of simulation models

and improve the precision of gas concentration predictions. In response to these challenges

prospects are presented for future research involving multidisciplinary approaches and the integration of data-driven methods with physical modeling. This paper contributes to enhancing the detection and maintenance capabilities of oil-paper insulation systems and offers theoretical supports for the intelligent operation and maintenance of electrical equipment.