For the purpose of improving the quality of multi-strand carbon fiber wires, the detection method of latent defects of multi-strand carbon fiber wires considering high-precision temperature sensors is studied. The high-precision temperature sensor is designed by using Brillouin optical time-domain reflection technology; An optical fiber is implanted in a multi-strand carbon fiber wire, and a narrow spectrum light source is injected into the optical fiber; The high-precision temperature sensor uses the heterodyne detection method to process the narrow-spectrum light source and obtain the temperature acquisition results of multi-strand carbon fiber wires; The internal noise of the collected temperature data is filtered by the average processing method; According to the filtered temperature data, the inverse problem model of temperature field of multi-strand carbon fiber wire is established; Newton iteration method is used to solve the model, and the thermal conductivity of multi-strand carbon fiber wire is obtained; Compare and analyze the solved thermal conductivity with the thermal conductivity of the defect-free conductor to complete the detection of latent defects. The experiment shows that this method can effectively collect the temperature of multi-strand carbon fiber wire and filter its internal noise; This method can effectively detect the latent defects of conductors; The higher the load current of the injected wire, the better the detection effect of the latent defect.