To reduce the output noise in the low-frequency band of the actuator actuation circuit of a space inertial sensor for gravitational wave detection, we designed a closed-loop actuation circuit to enhance the stability of the system by adjusting the output in real time through a feedback mechanism. First, we designed both open-loop and closed-loop actuator actuation circuits. Second, the low-frequency noise in the millihertz band of each unit of the actuation circuit was analyzed in detail. Last, the Simulink model is employed to analyze both models’ DC low-frequency output noise, assessing their precision and stability. The experimental results show that the peak voltage noise power spectral density (PSD) of the closed-loop actuation circuit is \(10.3\,{\upmu }{\text{V/Hz}}^{{1/2}}\) for DC 10 V output in the range of 1 MHz–0.1 Hz, and the peak voltage noise PSD of the open-loop actuation circuit is \( 18.1\,{\upmu }{\text{V/Hz}}^{{{\text{1/2}}}} \) for DC 10 V output, and the closed-loop actuation circuit has a lower noise and better stability.