In this paper,a sensor system for the internet of things under ex treme environment is developed based on the power-over-fiber technique.Via this technique,high laser power is transmitted over fiber link,and is converted into electric energy by photovolta ic power converter (PPC) at the end of the link.As the fiber is inherently immune to electroma gnetic interference, the converted electric energy drives sensor nodes safely.To improve the power- supply efficiency,the impedance-matching tracking method is proposed to enable the maximum electric p ower output of the PPC for any load.Based on this method,a smart power manager is realized to sto re the electric energy and an appropriate voltage is set to drive the sensor nodes.Moreover,a simple and reliable communication protocol is proposed to adjust the working mode of the sensor node s.In this way, the power consumption of nodes is reduced and the applicable ability of the sys tem is enhanced. In the power-over-fiber sensor system constructed in this paper,the maximum e lectric energy output of PPC is 555mW when the incident optical power is 1.5W,and the effective opti cal-electric conversion efficiency is 37%.The system can sample,process and display sensing information stably over a distance of 2km.Such a system affords a novel solution to realize the internet of things safely and reliably.