The joints of Cross Linked Poly Ethylene (XLPE) power cables often suffer the frequent faults and latent defects, which can be detected effectively by partial discharge (PD). In this study, a novel capacitive strip sensor for PD measurement is proposed and testified under the context of prefabricated 110kV XLPE cable joints. Firstly, a simulation model based on Finite Integration Technique (FIT) is established. Then the transmission mode and the frequency spectrum of the electromagnetic wave related to the PD signal is investigated. Furthermore, the energy distribution of PD signal among the cable joint is analyzed to identify the optimal position of installation. Finally, a real capacitive strip PD detection sensor is deployed on a 110kV XLPE cable system and comparative tests with a standard sensor are conducted. Consistent experimental results have been observed and a sensitivity better than 5 pC has been achieved on the proposed capacitive strip sensor, which clearly shows its potential on online PD monitoring for high voltage power cable joints.