The invention belongs to the technical field of measuring, especially relates to a ground resistance online measuring instrument, and discloses a ground resistance online measuring instrument advantaged in high measuring precision. The ground resistance online measuring instrument comprises a single-chip microcomputer, a display, a keyboard, a hardware control and protection part, a current acquisition part, a voltage acquisition part, a voltage analog signal processing part and a current analog signal processing part, and is mainly structurally characterized in that the single-chip microcomputer is respectively connected with the display, the keyboard, the hardware control and protection part, the current acquisition part and the voltage acquisition part, the current acquisition part is connected with the current analog signal processing part, and the voltage acquisition part is connected with the voltage analog signal processing part.