Insulation resistance measuring circuit and high voltage insulation monitoring system of electric vehicle

The utility model relates to an insulation resistance measuring circuit and a high voltage insulation monitoring system of electric vehicle; the insulation resistance measuring circuit comprises a resistor R1 and a resistor R2 connected with an electric vehicle cell pack so as to form a monitoring loop; the resistors R1 and R2 are connected in series in sequence between an anode and a cathode of the cell pack; a switch S1 is arranged between the R1 and the anode of the cell pack; a switch S2 is arranged between the R2 and the cathode of the cell pack; connecting ends of the R1 and R2 are connected with a vehicle body of the electric vehicle; the R1 and R2 are respectively connected in parallel with a first voltage sampling device and a second voltage sampling device. The high voltage insulation monitoring system comprises the insulation resistance measuring circuit and a control circuit; the insulation resistance measuring circuit and the high voltage insulation monitoring system employ a divider resistance mode to monitor the insulation resistance; the circuit is simple and easy to apply, and low in cost.