According to the requirement of national information security, a cable detector based on Loongson 2H is designed. The cable detector consists of CPU processing unit, FPGA logic control unit, conductive resistance detection circuit and insulation resistance detection circuit. CPU processing unit processor uses domestic Loongson 2H chip, which has strong expansion ability and provides common external interface. The FPGA logic control unit mainly realizes the control of the interface, the digital acquisition signal processing and the communication of CPU processing unit. The conductivity detection circuit adopts the Kelvin 4 wires method to effectively eliminate the impedance at both ends of the test line and improve the measurement accuracy. The insulation resistance is measured by the method of partial pressure, and the high voltage dc voltage is reduced and then transferred to FPGA after AD conversion. With the method of transfer switch reuse, reduce the number of the relay, reduces the equipment cost and volume, reduce the power consumption of the engine, and increases the life span of the equipment and the safety of the measurement site. The application results show that the cable detector based on Loongson 2H is practical and has good application value.