With the large-scale integration of high-penetration renewable energy units into power systems, the transient voltage stability of power grids faces severe challenges. Recent analyses of multiple renewable energy disconnection incidents reveal that large-scale disconnections exhibit a “low-voltage + high-voltage” composite characteristic, highlighting the critical importance of comprehensive transient voltage ride-through (TVRT) capability in modern power systems. As low-voltage ride-through (LVRT) capability testing for renewable energy units becomes widespread, high-voltage issues have gradually emerged as one of the primary causes of renewable energy disconnections in the current stage, underscoring the urgent need for integrated high-low transient voltage testing systems. Existing transient voltage simulation systems predominantly focus on single low-voltage scenarios, lacking integrated high-low transient voltage regulation capabilities and suffering from limitations such as low control efficiency and high equipment losses. This paper proposes a magnetically controlled reactor-based (MCR) high-low transient voltage simulation and regulation system, achieving bidirectional precise transient voltage control through innovative topology design and control methods. Experimental results demonstrate that the system enables three-phase independent control and provides a voltage testing range of 0.145 p.u. to 1.6 p.u. Magnetically controlled reactors replace traditional mechanical taps, enabling smooth reactance adjustment via control modules, thereby avoiding arcing and voltage/current stress impacts while enhancing equipment lifespan. In addition, it supports three-phase independent control to simulate both symmetrical and asymmetrical fault scenarios, adapting to complex grid conditions.