Abstract: The existence of mining car changes figure and size of cross section of coal mine laneway,so it influences transmission characteristics of electromagnetic wave.The paper measured the influence of mining car on transmission characteristics of electromagnetic wave in coal mine laneway on the site and analyzed measured data in details.The measuring result showed that transmission attenuation of electromagnetic wave has relation with the length of carriage and the transmission frequency,the existence of mining car makes increase of transmission attenuation of electromagnetic wave.In range of 50～(900 MHz,) the higher the frequency of electromagnetic wave is and the smaller the attenuation is,the more propitious they are to transmit electromagnetic wave.