Abstract: The research of measuring while drilling (MWD) technology for underground coal mines is later in China, for many years, the directional drilling equipment and instruments mainly rely on importation.Based on our newly developed MWD directional drilling system tested in Ningxia Rujigou coal mine, the paper summed up the composition, performance application of the home system.The parameters of borehole trajectory obtained by MWD were processed and analyzed, providing references for the design of directional borehole trajectory and analysis of measured trajectory in the future.The results of application of the system indicated that both the system and software could meet MWD requirements in underground coal mines.