In order to monitor the battery information of portable photoelectric sighting telescope, considering the requirement of low power consumption and small size of photoelectric sighting telescope, it’s proposed that a structure of battery monitoring system using single-chip FPGA as processor. Two 18650 series battery packs are monitored in real time by the system, Battery information and image information are superimposed synchronously by FPGA, and displayed on OLED screen. Surplus electricity、battery temperature、voltage and current can be seen intuitively on the display screen. When the electricity is insufficient or the current/voltage is abnormal，the corresponding warning is given by reddening the font color。After repeated system experiments，the battery monitoring system of photoelectric sighting telescope has the characteristics of high accuracy and stability，it has engineering practicability.