Abstract: Ring currents, an important current system formed by the azimuthal drift of charged particles in planetary magnetospheres, play a key role in disturbing planetary magnetic fields and driving magnetospheric dynamics. This paper systematically reviews recent research progress on the basic features and dynamic processes of ring currents around Earth, Mercury, Jupiter, and Saturn. For Earth's ring current, the contribution ratio of oxygen ions to the plasma pressure and energy density during geomagnetic storms significantly increases, and their loss mechanisms (such as charge exchange) have also been further discussed. In addition, the impact of geomagnetic substorms on the overall intensity, time variations, and spatial distributions of ring currents (such as enhancing dusk side ring currents via particle injections) has also been extensively studied. Further analysis confirms that the impacts of these two factors are not independent, but have positive relations: the energy density ratio of oxygen ions also increases during geomagnetic substorms. The existence of a ring current around Mercury had not been confirmed before. However, using observations from the MESSENGER spacecraft and test particle simulations, recent studies have, for the first time, both observationally and theoretically discovered and confirmed the existence of ring currents that are formed by energetic protons orbiting along the Shabansky orbits. The basic characteristics of Mercury magnetic storms during strong solar activity periods are further studied. Research on the ring currents of Jupiter and Saturn relies highly on the datasets. Thanks to the rich data information provided by the Juno and Cassini spacecraft, recent research has, on the basis of previous results, obtained further conclusions on the giants’ ring current. For Jupiter, the co-rotation characteristics, the dominant plasma component and their proportions, the spatial distributions, as well as the overall structure of the current sheet from the IO orbit to near the dawn side magnetopause have been established. For Saturn, studies have revealed its bowl-shaped ring current structure, ENA features, and the 11-year variation cycles. Despite these significant advances, many questions about planetary ring currents remain unresolved, including: (1) the causal relationship between a high ratio of oxygen ions and ring current intensification during intense geomagnetic storms; (2) the response of Mercury’s ring current to solar wind variations and the specific processes during Mercury’s magnetic storms; and (3) the differences in the structure and dynamics of ring currents among giant planets. Future satellite missions will provide novel observational data for ring current research, driving new breakthroughs in the discovery of planetary ring currents.