The invention discloses a potential difference meter with three measuring panels, which is used for measuring direct voltage. A first step panel of the potential difference meter consists of a 22*10 ohm measuring panel, a second step panel consists of a measuring panel formed by a 11*11 ohm annular resistor grid, 10 resistors of 0.5 ohm form an auxiliary panel, the third panel is a double-slide wire panel, and the two measuring panels are connected with a measuring slide wire by a conducting wire. Without switch changeover, the potential difference meter has no variation and is not affected by thermal electric potential during measuring, and saves two auxiliary panels of the first step panel.