Abstract: High voltage direct current(HVDC) cable is an important equipment for high voltage transmission and new energy access. Space charge accumulation will affect the internal electric field distribution of cable insulation, aggravate insulation aging and increase the risk of break-down failure. Therefore, it is a key index to evaluate the insulation health of cables and accessories, which are the biggest weak link of the whole cable system. However, due to the limitation of measurement principle and equipment size, the traditional pulsed electro-acoustic(PEA) device for space charge detection can not monitor the service cable in real time. The thickness of the electrode is greatly reduced by replacing the carbon black semi-conductive material with the sound speed of about one-third of the traditional aluminum electrode. By redesigning the electrode structure, the measurement system volume is reduced, pulse is injected from the cable accessory body, and PP coupling layer is added between the pulse injection point and the electrode to realize signal isolation, and effectively simplify the structure of the overall measurement system. Then the distortion of PEA signal in multilayer media is analyzed and corrected. Finally, the formation and accumulation of interface charges can be clearly observed by space charge detection of 10 kV cable intermediate joint, which verifies the effectiveness of the new detection device.