Rotating mirror Q-switched technology incurs no intracavity insertion loss， making it a direct method for obtaining narrow pulses and high peak power output lasers. Nanosecond pulses require the use of high-speed rotating mirror Q-switch， along with precise control of motor speed and xenon lamp discharge delay. This ensures maximum population inversion of in the laser medium， leading to the highest laser energy output. This paper presented the design of a high-speed rotating mirror Q-switched control system with the Arduino Mega 2560 microcontroller as its core. The system utilized precise parse of serial screen instructions by the microcontroller to control the charging and discharging of the laser power supply and the start-stop operations of the high-speed motor. Additionally， it integrated and downshifted the pulse signals from the rotating mirror to control the precise delay time for triggering the xenon lamp discharge， thereby achieving precise control over the delay time for the nanosecond narrow pulse Q-switched output of the lamp-pumped Er，Cr：YSGG laser. The highest single-pulse laser energy of 45.7 mJ， pulse width of 86.2 ns， and corresponding peak power of 530.2 kW were obtained at a repetition frequency of 5 Hz with a rotating mirror speed of 650 r/s.