The current long-distance signal transmission method does not realize parallelism between the transmission channel energy and transmission channel signals, which leads to high distortion of long-distance signal transmissions. To improve the long-distance transmission efficiency of seismic signals, in this paper, we propose a new technique for long-distance signal transmission in the seismic monitoring systems of high-speed railways. By adopting a method using parallel seismic signal energies in the signal transmission channel and parallel signal transmission structures in the transmission channel, we realize the bidirectional transmission of signals in the transmission channel. Based on the channel energy transmission structure and the signal transmission process, we made the transmission channel energy and signal parallel, and controlled the distortion of seismic signals in long-distance transmissions of high-speed railways. The experimental results show that the proposed method has a low packet-loss rate of about 3% and a long-distance transmission delay of only 0.9 s. This represents a low-error and high-efficiency long-distance transmission method for seismic signals in high-speed railways.