Solid nanogenerators often have a limited charge transfer due to the low contact area. Compared with solid-solid or solid-liquid nanogenerators, liquid-liquid nanogenerators can effectively increase the transferred charge. Limited by the fluidity of the liquid, the precise manipulation of the liquid morphology remains a challenge. In this work, using the surface tension of the droplet to fix the shape, we designed a new liquid-liquid triboelectric nanogenerator by using the immiscible aqueous-aqueous interface, achieving the contact surface charge transfer of 129 nC of a single droplet. This liquid-liquid nanogenerator has been proven to be applicable in humid environments, and the two-phase materials have good biocompatibility and can be used as a good carrier for drugs. Therefore, this nanogenerator is useful for future design of implantable devices and the design of a new type of bionic fully self-powered system has great potential. Meanwhile, such design established the foundation of aqueous electronics and more creation can be achieved by using this route.