This paper introduces a transmission line ice detection system，which consists of simulation wire, fiber optic ice sensor, signal sampling and processing system. To simulate the ice conditions of the transmission line, simulation wire are installed from a safe distance of the transmission line ,which sizes are same . Fiber optic ice sensors belong to reflection and reflective light intensity sensors, which installed in the different positions of simulated wire to detect the multipoints icing conditions of simulated wire. Through the icing conditions of simulated wire, the icing conditions of transmission line can be predicted. Experimental results show that the system has a good prospect and the advantages of wide measuring range, high sensitivity, structural integration, easy installation, etc.