The invention discloses a live detection system for DC cable leakage current. The DC cable leakage current live detection system comprises a micro-current sensor, a difference amplification and filtering module, an A/D module, a DSP control circuit, a display module and a communication module; the micro-current sensor transmits a detected current analog signal to the difference amplification and filtering module; the difference amplification and filtering module generates an amplified analog signal and transmits the amplified analog signal to the A/D module; the A/D module transmits a digital signal to the DSP control circuit; the DSP control circuit processes the digital signal to generate a control signal and a transmission signal; the control signal is fed back to the difference amplification and filtering module; the DSP control circuit displays the transmission signal through the display module; and the DSP control circuit performs communication on the transmission signal through the communication module. The live detection system can effectively and reliably detect an insulation state of a DC cable system and can guarantee power supply safety of a power grid.