A method to use laser to supply power remotely for multinode wireless sensor networks is proposed in this paper. In the working space of wireless sensor networks, laser is transformed to a spatial distributed light field with certain uniformity and its wavelength is converted to the most sensitive wavelength of solar cell by the phosphor element. Thus, more wireless sensor networks nodes can be powered at the same time. A demonstration experiment is carried out, an yttrium aluminum garnet phosphor element is stimulated by the 3 W 457 nm laser and a uniform diffused light field with 3 π/4 space angle is obtained. The average optical energy density is 85 μ W/cm2 at the distance 1.5 m away from the phosphor surface. An ultra low-power consumption energy harvesting system is designed. Under the radiation of remote laser power supply, characteristics of the energy harvesting system are tested. The result is that the system can supply 92.1 mJ during 0.7 s which can provide enough energy for WSN node. Preliminary result of a real-life application in an oil cellar is also given. As a novel power supply method for wireless sensor networks, it is a good active power supply candidate for wireless sensor networks when the environment energy field is not strong enough.