The embodiment of the invention discloses a battery system insulation detection device and relates to the field of electricity, and a detection circuit of the battery system insulation detection device can be simplified. The device comprises a voltage signal source used for providing a measurement voltage signal, and a measuring circuit which comprises a positive electrode node used for connectingwith a positive electrode of a battery system, a negative electrode node used for connecting with a negative electrode of the battery system, a grounding node used for being grounded, and an output measurement resistor. A first measuring resistor and a second measuring resistor are connected in series between the positive electrode node and the negative electrode node, one end of the output detection resistor is connected between the first measuring resistor and the second measuring resistor, and the other end of the output detection resistor is connected with the grounding node. The batterysystem insulation detection device further comprises a voltage measuring unit which is connected with a processing unit and is used for measuring a target voltage applied to the output detection resistor, and a processing unit which is used for calculating an insulation resistance value of the battery system. The battery system insulation detection device is mainly used for detecting the insulation resistance value and an electric leakage position of the battery system.