The invention discloses a multifunctional insulation detector suitable for DC power supply systems. The multifunctional insulation detector is characterized in that the detector includes an MCU (Master Control Unit), a balance bridge circuit and a sampling module thereof, an unbalanced bridge circuit and a sampling module thereof, an unbalanced bridge switching module, a DC leakage current amplifying and sampling module, a branch leakage current inspecting and switching module, an AC intrusion measurement module, a communication module and a magnetic holding hard node module; the output ends of the balance bridge circuit and the sampling module thereof, the unbalanced bridge circuit and the sampling module thereof, the DC leakage current amplifying and sampling module and the AC intrusionmeasurement module are connected with the MCU; the unbalanced bridge switching module, the branch leakage current inspecting and switching module and the magnetic holding hard node module are connected with the output end of the MCU; and the MCU is further connected with the communication module. The values of voltages to ground of a bus and branches thereof can be detected in real time and accurately, and therefore, the resistance to ground can be detected by solving a balance equation and an unbalanced equation.