Circuit structure for expanding direct-current micro-current measuring range and micro-current measuring instrument

The invention relates to a circuit structure for expanding a direct current micro-current measuring range and a micro-current measuring instrument, the circuit structure comprises L first standard resistors which are respectively connected in series with a small signal relay, and the L first standard resistors which are connected in series with the small signal relays are connected in parallel to form a first circuit; one of the Z high-insulation type relays is connected with the first circuit in series to form a second circuit, and the rest of the high-insulation type relays are respectively connected with a second standard resistor in series and then are connected in parallel, and are connected with the second circuit and X circuits which only comprise a third standard resistor in parallel. According to the invention, the wide-range coverage of the measuring range is realized, the current measurement precision is improved, the use number of high-insulation relays is reduced to the maximum extent, and the de