Human bone joint monitoring is essential for medical treatment, especially in the recovery phase of injury. It is worth noting that bending sensors based on soft robots have developed rapidly in recent years. Due to their flexibility, soft robots have a limitless number of degrees of freedom, but they also confront severe sensing and control issues. Meanwhile, triboelectric nanogenerators (TENGs) are projected to be self-powered sensors for soft robotics owing to their great sensitivity, versatility and simplicity. In this work, we first propose a triboelectric joint sensor (TJS) based on the TENG device. The TJS can provide the response on the dynamic, and the TJS’s output voltage is proportional to the local bending angle. According to the results, the voltage of TJS device rises linearly from 3.6[Formula: see text]V to 45[Formula: see text]V as the bending angle increases from 0∘ to 60∘. Furthermore, the TJS device can be used to monitor the postoperative rehabilitation of hand joints through the voltage signal of TJS device installed on the finger. This study will promote the application of triboelectric sensor simulating soft robot device in the field of medical monitoring.