The invention discloses an underground coal mine logging-while-drilling tool based on electromagnetic wave resistivity comprising a power supply circuit module, a transmitter module, a reception and preprocessing module and a digital signal processing module. The power supply circuit module is connected to the transmitter module, the reception and preprocessing module and the digital signal processing module. The transmitter module and the reception and preprocessing module are both connected to the digital signal processing module. The invention discloses a measuring method of the underground coal mine logging-while-drilling tool based on electromagnetic wave resistivity. By use of electromagnetic wave propagation in media, relative change of two characteristic parameters (phase difference and amplitude ratio) of an electromagnetic field is measured. The tool does not rely on well fluid as transmission medium so that the tool can be applied to dry hole measurement or high resolution and deep detection requirement.