The invention relates to an underground digital direct current electrical method meter. At present, a special direct current electrical method instrument for exploring the geological structure underground in a coal mine is usually communicated with a computer by adopting an RS232 mode, which is not compatible with the communication of a new computer system; a 51-series singlechip is used as a core chip, which has the defects of large power consumption, small storage capacity, low processing speed, and the like; a display screen is generally too small and is difficult for observation, and an external light is needed for illumination; key operations are inconvenient; and the shell of the instrument is heavy. The underground digital direct current electrical method meter provided by the invention comprises a power supply electrode A, a power supply electrode B, a power supply electrode M, a power supply electrode N, a battery set, an isolation booster circuit, a current limiting circuit, a current sampling circuit, a V/F (Voltage/Frequency) conversion circuit, an STM32 microcontroller, an A/D conversion circuit and a preamplification and impedance conversion circuit. The underground digital direct current electrical method meter is communicated with a computer system by adopting a USB and has the advantages of low power consumption, high processing speed, convenience for key operation and light shell, and a large-screen LED backlight liquid crystal display screen is used as an interface.