To meet the application requirements for continuous variable thrust capability and high-resolution characteristics for ion thrusters in drag-free flight missions of gravity gradient measurement satellites and precise orbit maintenance missions of near-Earth high-resolution observation satellites, the technical research on a high-resolution wide-range variable thrust ion thruster and its application verification are conducted. Leveraging the weak coupling and relative independence between the two critical physical processes of plasma discharge and ion beam extraction in Kaufman-type ion thrusters, a wide-range variable thrust ion thruster technical scheme with a divergent magnetic field configuration is proposed. The key technical investigations include wide-range discharge stability in the discharge chamber, a concave spherical ion optical system configuration design balancing wide-temperature-range ignition and high-density extraction requirements, and hollow cathode current emission continuity design. The discharge chamber structure based on a divergent magnetic field configuration can rapidly adjust plasma density under varying discharge intensities through optimal coordination of anode gas supply, magnetic induction intensity, and anode current, while resolving critical technical challenges in low-power discharge stability and high-power operational reliability. Adopting a concave spherical ion optical system, the technical challenge in matching grid thermal deformation spacing with the reliable extraction of high-density ion beams is addressed. The concave spherical configuration can realize full-power ion beam extraction within approximately 10 s in low-temperature environments. Meanwhile, the hollow cathode based on a lanthanum hexaboride (LaB₆) emitter, through redundant design of emitter thickness and adaptive design of the cathode orifice aspect ratio, not only extends the emitter evaporation loss lifespan but also achieves stable operation within an emission current range of 0.5–3.4 A. Based on this, the design optimization and ground-based performance evaluation of a 10-cm-aperture high-resolution wide-range continuously variable thrust ion thruster are completed (In fact, such an ion thruster already achieved on-orbit flight in 2023.). Satellite on-orbit test results indicate that the 10-cm-aperture thruster achieves thrust regulation of 1.39–20.05 mN within a power range of 98.3–585.3 W, with specific impulse maintained at 547–3056 s, consistent with ground test results. The thrust response rate reaches approximately 3 mN/s, and thrust resolution exceeds 15 μN, outperforming ground test metrics. Compared with traditional chemical propulsion systems used for satellite orbit control, this thruster improves orbit maintenance accuracy by two orders of magnitude, effectively ensuring the implementation of satellite’s on-orbit engineering missions.