In-vivo devices and systems are extensively used in medical field to real-time detect and adjust the physiological status of human being, but supplying energy in-vivo for these devices and systems is still a great challenge. In this work, we first developed a new kind of wireless nanogenerator (WLNG) based on biocompatible BZT-BCT nanowires (NWs). It works through compressing and releasing BZT-BCT NWs/PDMS nanocomposite by a changing magnetic field in wireless non-contact mode. The maximum output voltage reaches 3.9V, and the maximum output current is 1.17μA, which are 21.9% larger than the reported maximum output voltage 3.2V and 23.4 times of the reported maximum 50nA of non-contact nanogenerator. And we further integrated it with a new kind of transmitter into a wireless, power-free and implantable nanosystem for in-vivo biodetection. This nanosystem does not need any electrical power. An in-vitro changing magnetic field can be used to drive it to detect the variation of resistance in-vivo and wirelessly transmit the signal to the equipments in-vitro.