Abstract: In order to solve the electromagnetic interference problem of train to wayside communication for signal system in Beijing medium and low speed maglev transit demonstration line (Beijing urban S1 line), Through field test, experiment and theoretical analysis, the paper determined the cause of electromagnetic interference, proposed corresponding measures of interference suppression. The measures achieved good effect and guaranteed the stable operation of Beijing urban S1 line. The research and measures provided experiences for construction and maintenance of medium and low maglev transit.