The relay node is the transit center of the sensor Internet of Things communication, and the rationality of its selection is of great significance to ensure the stability of the Internet of Things communication and information throughput. This paper proposes a method of selecting relay nodes based on optical fiber to maximize the throughput of the sensing Internet of Things. By building a sensor Internet of Things model, find the main lobe in the target fiber sensor base station, and identify the signal transmitted by the light source node. Select the relay nodes that can transmit the known optical channel status to other nodes in the candidate nodes, remove the nodes that cannot maximize the throughput, obtain the average received signal to noise ratio of the sensor Internet of Things based on statistical independent distribution, and select the appropriate fiber sensor antenna to complete the relay node selection. Simulation results show that the outage probability of the proposed method approaches zero when the number of nodes is 22;When the power of the light source node is 30 dBm, the network throughput reaches 98%.