This application provides a signal transmission method and system, and relates to the field of communications technologies. The system includes an equalization module, a first decoder, and a feedback module. The equalization module includes at least two multi-symbol detectors. The feedback module is connected to the first decoder and the at least two multi-symbol detectors. The equalization module performs equalization processing on convolutional data flows to obtain an equalized data flow. In this process, each multi-symbol detector performs multi-symbol detection processing on a convolutional data flow input into the multi-symbol detector. The first decoder decodes the equalized data flow to obtain a decoded data flow. The feedback module feeds back a feedback data flow to the at least two multi-symbol detectors. The equalization module performs equalization processing on the convolutional data flows based on the feedback data flow.