Space solar array simulator(SSAS) is a key power input device for spacecraft power supply testing. SSASs are also required to simulate the steady-state I-V curve with a high tangent slope of the aerospace solar panel output and to have the dynamic response performance of the fast convergence to switching working point under a spacecraft power supply test environment. This paper proposes a high-linearized and fast-convergent RmI(HLFC-RmI) look-up table control method, which is aimed at solving these problems. This study converts the conventional voltage-current UI data table into the corresponding impedance-current RmI data table without adding any auxiliary hardware circuit. The RmI data table is used as a target form for I-V outer loop control, by using the proposed equivalent impedance Rm linearization formula, thereby achieving the simulation of a high tangent slope I-V curve. In the process of looking up table control, the optimized equivalent impedance Rm_real-time linearization formula is used to approximate the high-speed convergence characteristics of the UI look-up table method under constant-voltage load switching conditions. The new I-V outer loop control method is applied to a 1 kW hardware power platform of SSAS. The SSAS can not only simulate an arbitrary I-V curve with a high tangent slope but also has the characteristics of high-speed convergence of the switching working point.