The utility model provides a weak current signal transmission line for turn-to-turn insulation detection of a dry reactor. The transmission line comprises a transmission line force bearing body, a wire is wound on the outer surface of the transmission line force bearing body, the wire is periodically and repeatedly wound on the surface of the transmission line force bearing body in a forward winding and reverse winding alternating and continuous mode, and an insulating encapsulation layer is encapsulated on the outer surface of the wound transmission line. According to the transmission line, the induced voltage in a strong electromagnetic environment is greatly reduced and cancelled out; the electromagnetic interference noise of the environment does not influence the weak electric signalsof the thermistor wire and the thermosensitive thermocouple wire, and the inductance characteristic of the solenoid-like structure can effectively filter the AC and high-frequency signal interference,thereby further ensuring the signal transmission precision and stability of the transmission line fundamentally. The method is suitable for the field of online monitoring low-frequency (or direct-current) and weak-current signal transmission of power grids and power systems with high reliability requirements in a complex electromagnetic environment.