To improve the quality of multi-strand carbon fiber wires, a method for detecting latent defects in multi-strand carbon fiber wires based on high-precision temperature sensors is studied. Design a high-precision temperature sensor using Brillouin optical timedomain reflection technology, and implant a single fiber into multiple carbon fiber wires to achieve temperature collection by injecting a narrow spectral light source. Using heterodyne detection method to process narrow-spectrum light sources and obtain temperature collection results of multi-strand carbon fiber wires. Using an average processing method to filter out internal noise in temperature data. Based on the filtered temperature data, the inverse problem model of the temperature field of the multi strand carbon fiber conductor is established, and the Newton Iterative method is used to solve the model, so as to obtain the thermal conductivity of the multi strand carbon fiber conductor. Experiments have shown that this method can effectively collect the temperature of multiple carbon fiber wires and successfully filter out 99% of internal noise. The thermal conductivity of detecting defect free multi stranded carbon fiber wires is 235 W/ m·k. Based on this, this method can also effectively detect latent defects in wires based on the difference in thermal conductivity compared to defect free wires. It is worth noting that the method performs better in detecting latent defects when the load current of the wire increases.